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TROJ_ZOLPIC.AB

October 09, 2012
 Analysis by: Mark Joseph Manahan
 ALIASES:

TrojanDropper:Win32/Zolpiq.A (Microsoft), Trojan.Dropper (Symantec)

 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 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.

It executes then deletes itself afterward.

It modifies files, disabling programs and applications from properly running.

  TECHNICAL DETAILS

File Size:

110,592 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Aug 2012

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.

Installation

This Trojan drops the following files:

  • %System%\tpgenlic.dll
  • %System%\rappmts.hlp

(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 executes then deletes itself afterward.

Autostart Technique

This Trojan registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_WMDMPMSN

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WmdmPmSN\Enum

Other System Modifications

This Trojan modifies the following files:

  • %System%\mspmsnsv.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 connects to the following possibly malicious URL:

  • str.{BLOCKED}nction.com

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.358.02

FIRST VSAPI PATTERN DATE:

29 Aug 2012

VSAPI OPR PATTERN File:

9.359.00

VSAPI OPR PATTERN Date:

30 Aug 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

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root
    • LEGACY_WMDMPMSN
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WmdmPmSN
    • Enum

Step 4

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%\tpgenlic.dll
  • %System%\rappmts.hlp

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_ZOLPIC.AB. 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.

Step 6

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

  • %System%\mspmsnsv.dll


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