Analysis by: Mark Joseph Manahan
ALIASES:

Trojan:MSIL/Agent

 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

Infection Channel: Spammed via email, Dropped by other malware, Downloaded from the Internet

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 65,536 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Sep 2012
Payload: Connects to URLs/IPs, Downloads files

Arrival Details

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

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

Autostart Technique

This Trojan enables its automatic execution at every system startup by dropping the following copies of itself into the Windows Common Startup folder:

  • %User Profile%\svchost.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • {BLOCKED}sblog.{BLOCKED}ebhost.com/blog/bot.php?question=update

As of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.426.07
FIRST VSAPI PATTERN DATE: 28 Sep 2012
VSAPI OPR PATTERN File: 9.427.00
VSAPI OPR PATTERN Date: 28 Sep 2012

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

Identify and terminate files detected as TROJ_MSIL.ADL

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_MSIL.ADL 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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