Virus:Worm/Sohanad.S
Date discovered:01/09/2008
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:315.905 Bytes
MD5 checksum:37091432f5e73c8f0E407c10a0b0b84f
VDF version:7.00.06.99
IVDF version:7.00.06.100 - Monday, September 1, 2008

 General Method of propagation:
   • Messenger


Aliases:
   •  Symantec: W32.Svich
   •  Kaspersky: Trojan-Downloader.Win32.AutoIt.aa
   •  TrendMicro: WORM_SOHANAD.EI
   •  F-Secure: Trojan-Downloader.Win32.AutoIt.aa
   •  Sophos: W32/Sohana-Y
   •  Panda: W32/Sohanat.BY.worm
   •  Eset: Win32/Hakaglan.C
   •  Bitdefender: Trojan.Downloader.Autoit.V


Platforms / OS:
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Downloads files
   • Lowers security settings
   • Registry modification

 Files It copies itself to the following locations:
   • %SYSDIR%\SSCVIIHOST.exe
   • %WINDIR%\SSCVIIHOST.exe
   • %SYSDIR%\blastclnnn.exe



The following files are created:

– Non malicious file:
   • %SYSDIR%\setting.ini

– %WINDIR%\Tasks\At1.job File is a scheduled task that runs the malware at predefined times.
– %SYSDIR%\autorun.ini Further investigation pointed out that this file is malware, too. Detected as: TR/Autorun.A.2




It tries to download some files:

– The location is the following:
   • setting3.**********
At the time of writing this file was not online for further investigation.

– The location is the following:
   • http://www.freewebs.com/se**********
At the time of writing this file was not online for further investigation.

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

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   • Yahoo Messengger="%SYSDIR%\SSCVIIHOST.exe"



The following registry keys are added in order to load the service after reboot:

– [HKLM\SYSTEM\ControlSet001\Services\Schedule]
   • AtTaskMaxHours=dword:00000000



The following registry keys are changed:

Various Explorer settings:
– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
   New value:
   • NofolderOptions=dword:00000001

Disable Regedit and Task Manager:
– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System]
   New value:
   • DisableTaskMgr=dword:00000001
   • DisableRegistryTools=dword:00000001

– [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
   Old value:
   • "Shell"="Explorer.exe"
   New value:
   • Shell="Explorer.exe SSCVIIHOST.exe"

 Messenger It is spreading via Messenger. The characteristics are described below:

– Yahoo Messenger


To:
All entries in the contact list.


The received message may look like the following:


 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 the following runtime packer:
   • UPX

Description inserted by Alexandru Dinu on Tuesday, September 9, 2008
Description updated by Alexandru Dinu on Tuesday, September 9, 2008

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