TROJ_MONKIF.WC

October 08, 2012
 Analysis by: kathleenno
 ALIASES:

Downloader (Symantec); TrojanDropper:Win32/Monkif.J (Microsoft); Troj/Monkif-Fam (Sophos)

 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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

24,600 bytes

File Type:

DLL

Initial Samples Received Date:

29 Mar 2011

Payload:

Drops files

Installation

This Trojan drops the following files:

  • %User Temp%\msfat32 - detected as TROJ_MONKIF.SMAY

(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.)

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CLASSES_ROOT\PROTOCOLS\Filter\
text/html
(Default) = "Microsoft Improved HTML MIME Filter"

HKEY_CLASSES_ROOT\PROTOCOLS\Filter\
text/html
CLSID = "{random CLSID}"

Dropping Routine

This Trojan executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine:

8.900

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

Remove malware files dropped/downloaded by TROJ_MONKIF.WC

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_MONKIF.WC

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Delete this registry value

[ 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.

  • In HKEY_CLASSES_ROOT\PROTOCOLS\Filter\text/html
    • (Default) = Microsoft Improved HTML MIME Filter
  • In HKEY_CLASSES_ROOT\PROTOCOLS\Filter\text/html
    • CLSID = {random CLSID}

Step 6

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