Analysis by: Jasen Sumalapao
ALIASES:

Trojan:Win32/Agent.OO (Microsoft), Worm.Win32.AutoRun.ecj (Kaspersky), W32.Whybo.Z (Symantec), Generic Malware.ja (NAI), Mal/Packer (Sophos), BehavesLike.Win32.Malware.eah (mx-v) (Sunbelt), WORM/Rbot.Gen (Antivir), W32/Heuristic-210!Eldorado (Authentium), Dropped:BAT.Delete.YBC (Bitdefender), Trojan.Crypted-2 (Clamav), PossibleThreat (Fortinet), W32/Heuristic-210!Eldorado (not disinfectable) (Fprot), BehavesLikeWin32.Malware (Ikarus), a variant of Win32/Small.NO trojan (NOD32), Trojan.Win32.Small.102210 (VBA32)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes registry entries, causing some applications and programs to not function properly.

It connects to a website to send and receive information.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 25,088 bytes
File Type: EXE
Initial Samples Received Date: 15 Apr 2011

Arrival Details

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This worm drops a copy of itself in the following folders using different file names:

  • %System%\drivers\svchost.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following non-malicious file:

  • %User Temp%\rs.bat

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Autostart Technique

This worm modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
ImagePath = %SystemRoot%\system32\drivers\svchost.exe

(Note: The default value data of the said registry entry is %SystemRoot%\system32\drivers\svchost.exe -k netsvcs.)

Other System Modifications

This worm deletes the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv\Parameters
ServiceDll = %System%\wuauserv.dll

Backdoor Routine

This worm connects to the following websites to send and receive information:

  • {BLOCKED}99.{BLOCKED}8.org
  • {BLOCKED}99.{BLOCKED}8.org:80

Other Details

This worm deletes the initially executed copy of itself