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Date discovered:14/06/2011
In the wild:Yes
Reported Infections:Low
Distribution Potential:Low to medium
Damage Potential:Low to medium
Static file:Yes
VDF version:
IVDF version:

 General Method of propagation:
   • Autorun feature

   •  TrendMicro: WORM_VBNA.YRS
   •  Sophos: Mal/Behav-394
   •  Microsoft: Worm:Win32/Arhost

Platforms / OS:
   • Windows 2000
   • Windows XP
   • Windows 2003
   • Windows Vista
   • Windows 7

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

 Files It copies itself to the following location:
   • %APPDATA%\%random character string%.exe

The following file is created:

– %APPDATA%\%random character string% Contains parameters used by the malware.

 Registry To each registry key one of the values is added in order to run the processes after reboot:

–  [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   • "MSWUpdate"="\"%APPDATA%\%random character string%.exe\""

–  [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "MSWUpdate"="\"%APPDATA%\%random character string%.exe\""

The following registry key is added:

– [HKLM\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\
   • "C:\Documents and Settings\Use\Application Data\%random character string%.exe"="C:\Documents and Settings\Use\Application Data\%random character string%.exe:*:Enabled:CityScape"

The following registry key is changed:

– [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
   New value:
   • "Shell"="Explorer.exe \"%APPDATA%\%random character string%.exe\""

 Backdoor Contact server:
The following:
   • **********

 Miscellaneous  Checks for an internet connection by contacting the following web site:

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

Description inserted by Andrei Ilie on Wednesday, October 26, 2011
Description updated by Andrei Ilie on Monday, October 31, 2011

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