Analysis by: Cris Nowell Pantanilla
ALIASES:

Trojan.Win32.Inject.mvv [Kaspersky] Infostealer.Gampass [Symantec]

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 45,568 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 May 2011
Payload: Connects to URLs/IPs

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system:

  • %System%\Ir32_a.exe
  • %System%\Ir32_b.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,Ir32_b.exe"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}r.blog5566.com/images/yukor.bmp
  • http://{BLOCKED}r.blog5566.com/images/yukor.gif
  • http://{BLOCKED}r.blog5566.com/images/yukor.jpg

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.148.06
FIRST VSAPI PATTERN DATE: 10 May 2011

NOTES:

Trend customers:

    Keep your pattern and scan engine files updated. Trend Micro antivirus software can clean or remove most types of computer threats. Malware, though, such as Trojans, scripts, overwriting viruses and joke programs which are identified as uncleanable, should simply be deleted.

All Internet users:

  • Use HouseCall - the Trend Micro online threat scanner to check for malware that may already be on your PC.
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