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Virus:W32/Sohanad.R
Date discovered:19/07/2007
Type:Worm
In the wild:Yes
Reported Infections:Low to medium
Distribution Potential:Low
Damage Potential:Low to medium
Static file:No
File size:240.128 Bytes
IVDF version:6.39.00.168 - Thursday, July 19, 2007

 General Method of propagation:
   • No own spreading routine


Aliases:
   •  Symantec: W32.Svich
   •  Mcafee: W32/YahLover.worm virus
   •  Kaspersky: Trojan-Downloader.Win32.AutoIt.aa
   •  F-Secure: Trojan-Downloader.Win32.AutoIt.aa
   •  Sophos: W32/Sohana-R
   •  Panda: W32/Sohanat.BP.worm
   •  VirusBuster: Trojan.DL.AutoIt.DO
   •  Eset: Win32/Sohanad.NAK worm
   •  Bitdefender: Worm.IM.Agent.G


Platforms / OS:
   • Windows 95
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Downloads files
   • Drops a malicious file
   • Registry modification

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

%SYSDIR%\autorun.ini Further investigation pointed out that this file is malware, too. Detected as: INF/AutoRun.J




It tries to download some files:

– The location is the following:
   • http://nhatquanglan3.t35.com/**********.nql
It is saved on the local hard drive under: %temporary internet files%\Content.IE5\%random character string%\setting[1].nql At the time of writing this file was not online for further investigation.

– The location is the following:
   • http://nhatquanglan4.t35.com/**********.nql
It is saved on the local hard drive under: %temporary internet files%\Content.IE5\%random character string%\setting[1].nql

 Registry The following registry keys are added in order to run the processes after reboot:

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

– [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
   • "Shell"="Explorer.exe SSVICHOSST.exe"



The following registry keys are added:

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\
   WorkgroupCrawler\Shares]
   • "shared"="\New Folder.exe"

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
   • "NofolderOptions"=dword:00000001



The following registry keys are changed:

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

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

 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 Andreas Feuerstein on Tuesday, September 9, 2008
Description updated by Andreas Feuerstein on Tuesday, September 9, 2008

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