Analysis by: Michael Cabel
ALIASES:

Microsoft: TrojanDownloader:Win32/Chepvil.J; Kaspersky: Trojan-Downloader.Win32.Small.lav

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

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

  TECHNICAL DETAILS

File Size: 18,432 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 30 Mar 2011
Payload: Downloads files

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.

Download Routine

This Trojan saves the files it downloads using the following names:

  • %User Temp%\lol2.exe
  • %User Temp%\pod.exe
  • %User Temp%\spm.exe

(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.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This Trojan attempts to access the following websites to download files, which are possibly malicious:

  • http://{BLOCKED}.{BLOCKED}.220.52/lol2.exe
  • http://{BLOCKED}.{BLOCKED}.220.52/pod.exe
  • http://{BLOCKED}.{BLOCKED}.220.52/spm.exe
  • http://{BLOCKED}.{BLOCKED}.29.175/lol2.exe
  • http://{BLOCKED}.{BLOCKED}.29.175/pod.exe
  • http://{BLOCKED}.{BLOCKED}.29.175/spm.exe

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

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.938.13
FIRST VSAPI PATTERN DATE: 30 Mar 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.WXU. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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