Threat Encyclopedia

HTML_REDIR.AC

Malware type: HTML

Aliases: Exploit.HTML.Mht (Kaspersky), Exploit-MhtRedir.gen (McAfee), MHTMLRedir.Exploit (Symantec), HTML/Exploit.OBJ-Mht (Avira), Troj/Rider-I (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, ME, NT, 2000, XP

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Low

Distribution potential:

Low

Description: 

This is the Trend Micro detection for websites compromised by the insertion of an encrypted malicious JavaScript file.

The said script file checks for the affected system's web browser and its version. It then generates a random string based on the version, then appends the said string to a certain URL.

It then connects to the generated URL to possibly download other malicious files. As a result, routines of the downloaded files are also exhibited on the affected system.

For additional information about this threat, see:

Description created: May. 20, 2009 2:43:41 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  No

Size of malware: Varies

Initial samples received on: May 26, 2004

Payload 1: Downloads files

Details:

This is the Trend Micro detection for websites compromised by the insertion of an encrypted malicious JavaScript file.

The said script file checks for the affected system's web browser and its version. It then generates a random string based on the version.

The random string is appended to the following URL:

  • http://{BLOCKED}r.cn/rss/?id=

The resulting string is as follows:

  • http://{BLOCKED}r.cn/rss/?id={generated string}

It then connects to the generated URL to possibly download other malicious files. As a result, routines of the downloaded files are also exhibited on the affected system.

Analysis By: Karl Dominguez


SOLUTION


Minimum scan engine version needed: 6.500

Pattern file needed: 6.111.00

Pattern release date: May 5, 2009


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

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 1: Close all opened browser windows 

 Step 2: Scan your computer with your Trend Micro product to delete files detected as HTML_REDIR.AC  

*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.




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