Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Malagent (Microsoft)

 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

This Trojan may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size: 28,161 bytes
File Type: PE
File Compression: PECompact
Memory Resident: Yes
Initial Samples Received Date: 13 Dec 2010

Arrival Details

This Trojan may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %System%\userinit.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 files:

  • %System%\dhpxus.dll
  • %System%\sohdlx.dll

(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.)

Other Details

This Trojan does the following:

  • Overwrites %System%\userinit.exe which is a legitimate Microsoft file.

(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.)

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 7.701.00
VSAPI OPR PATTERN Date: 15 Dec 2010

Step 1

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

Step 2

Search and delete this file

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %System%\dhpxus.dll
  • %System%\sohdlx.dll

Step 3

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware/spyware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System%\userinit.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_VB.SMIS 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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