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HTML_MHTREDIR.FN

October 02, 2013
 ALIASES:

Exploit.HTML.Mht (Kaspersky), Exp/HTML.Mht.53 (Avira)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

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

  TECHNICAL DETAILS

File Size:

26,538 bytes

File Type:

HTML, HTM

Memory Resident:

Yes

Initial Samples Received Date:

09 Jan 2005

Arrival Details

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

Download Routine

This Trojan takes advantage of the following software vulnerabilities to download possibly malicious files:

  • MS04-013:Cumulative Security Update for Outlook Express (837009)

After successfully exploiting the said vulnerability, this malware connects to the following URLs to possibly download other malicious files:

  • http://{BLOCKED}/cj/css/HELP.TXT

It saves the files it downloads using the following names:

  • #.HTM

Trend Micro detects the dowloaded file as:

  • CHM_DELF.UP

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

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

3.150.01

FIRST VSAPI PATTERN DATE:

09 Jan 2006

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

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

  • HTML_MHTREDIR.FN


*Note: 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 3

Remove malware/grayware files dropped/downloaded by HTML_MHTREDIR.FN

  • CHM_DELF.UP

Step 4

Scan your computer with your Trend Micro product to delete files detected as HTML_MHTREDIR.FN. 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 5

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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