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Virus:Worm/Sohanad.Gen.13
Date discovered:16/02/2011
Type:Worm
In the wild:Yes
Reported Infections:Low to medium
Distribution Potential:Low to medium
Damage Potential:Low to medium
Static file:Yes
File size:490.557 Bytes
MD5 checksum:e4ee5c05e4edca467d379355b62d1fd8
VDF version:7.10.08.215
IVDF version:7.11.03.121 - Wednesday, February 16, 2011

 General Method of propagation:
   • Autorun feature


Aliases:
   •  Sophos: W32/Sohana-DG
   •  Bitdefender: Trojan.Autoit.ANN
   •  Panda: W32/Sohanat.KO
   •  GData: Trojan.Autoit.ANN


Platforms / OS:
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Drops malicious files
   • Lowers security settings
   • Registry modification

 Files It copies itself to the following locations:
   • %SYSDIR%\domain.exe
   • %SYSDIR%\win32\csrss.exe
   • %drive%\iostream.exe
   • %HOME%\Start Menu\Programs\Startup\domain.exe
   • %drive%\%all directories%\%directory name%.exe



It deletes the initially executed copy of itself.



It deletes the following file:
   • %SYSDIR%\csrss.exe



The following files are created:

%malware execution directory%\autorun.inf This is a non malicious text file with the following content:
   • %code that runs malware%

%drive%\autorun.inf This is a non malicious text file with the following content:
   • %code that runs malware%

%SYSDIR%\cmd.bat



It tries to execute the following files:

– Filename:
   • net user root /add


– Filename:
   • net user root 3645923527


– Filename:
   • net localgroup administrators root /add


– Filename:
   • explorer.exe /n, /root, %malware execution directory%


– Filename:
   • %SYSDIR%\win32\csrss.exe


– Filename:
   • net1 user root /add


– Filename:
   • net1 user root 3645923527


– Filename:
   • net1 localgroup administrators root /add


– Filename:
   • net user "%current username%" " taskmgr"


– Filename:
   • net1 user "%current username%" " taskmgr"

 Registry The following registry key is added in order to run the process after reboot:

– [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "%computer name%@%IP address%"="domain.exe"



The value of the following registry key is removed:

–  [HKCU\Software\Microsoft\Internet Explorer\Main]
   • Window Title



The following registry keys are added:

– [HKCU\Software\Microsoft\Command Processor]
   • "Autorun"="%SYSDIR%\cmd.bat"

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\
   Favorites\Favorites Bar]
   • "Order"=hex:08,00,00,00,02,00,00,00,74,00,00,00,01,00,00,00,01,00,00,00,68,00,00,00,00,00,00,00,5A,00,32,00,1A,01,00,00,F8,3A,CD,46,20,00,53,55,47,47,45,53,7E,31,2E,55,52,4C,00,00,3E,00,03,00,04,00,EF,BE,F8,3A,C5,46,F8,3A,C5,46,14,00,00,00,53,00,75,00,67,00,67,00,65,00,73,00,74,00,65,00,64,00,20,00,53,00,69,00,74,00,65,00,73,00,2E,00,75,00,72,00,6C,00,00,00,1C,00,00,00,00,00,00,00

– [HKLM\SOFTWARE\Microsoft\Internet Explorer\MAIN]
   • "FullScreen"="no"

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System]
   • "DisableRegistryTools"=dword:0x00000000
   • "DisableTaskMgr"=dword:0x00000000

– [HKLM\SYSTEM\CurrentControlSet\Services\Schedule]
   • "AtTaskMaxHours"=dword:0x00000000

– [HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server]
   • "EnableConcurrentSessions"=dword:0x00000009
   • "MaxOutstandingConnect"=dword:0x0000008f

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
   • "NofolderOptions"=dword:0x00000001

– [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\
   SpecialAccounts\UserList]
   • "root"=dword:0x00000000



The following registry keys are changed:

– [HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server]
   New value:
   • "fDenyTSConnections"=dword:0x00000000

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
   New value:
   • "Hidden"=dword:0x00000002
   • "HideFileExt"=dword:0x00000001

– [HKCU\Software\Microsoft\Internet Explorer\Main]
   New value:
   • "FullScreen"="no"
   • "Start Page"="http://www.google.com/"
   • "Window_Placement"=hex:2C,00,00,00,00,00,00,00,01,00,00,00,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,FF,8E,00,00,00,B1,00,00,00,AE,03,00,00,09,03,00,00

– [HKCU\Software\Microsoft\Internet Explorer\Toolbar]
   New value:
   • "Locked"=dword:0x00000001

 File details Programming language:
The malware program was written in MS Visual C++.


Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with a runtime packer.

Description inserted by Petre Galan on Wednesday, April 13, 2011
Description updated by Petre Galan on Thursday, April 14, 2011

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