Analysis by: kathleenno
ALIASES:

Troj/Dloadr-DHB (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

  TECHNICAL DETAILS

File Size: 151,552 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 Apr 2011
Payload: Drops files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Trojan drops the following files:

  • %User Temp%\$MsAutoUpdate.exe - also detected as TROJ_AGENTT.SC
  • %User Temp%\{malware filename} - non-malicious PDF file

(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 Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
ClsPack = %User Temp%\$MsAutoUpdate.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
ClsPack = %User Temp%\$MsAutoUpdate.exe