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JS_COSMU.A
Malware type: Trojan
Destructive: No
Platform: Windows 2000, XP, Server 2003
Encrypted: No
In the wild: Yes

Overview


This JavaScript has received attention from independent media sources and/or other security firms.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan may be unknowingly downloaded by a user while visiting malicious websites. It may be hosted on a website and run when a user accesses the said website.

It takes advantage of software vulnerabilities to allow a remote user or malware/grayware to download files.

Technical Details


File size: Varies
File type: Script
Memory resident: No
Initial samples received date: 17 Mar 2010
Payload: Downloads files

Arrival Details

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

It may be unknowingly downloaded by a user while visiting the following malicious websites:

  • http://{BLOCKED}istyle.com/wap/include/wj/ie.html?332

It may be hosted on a website and run when a user accesses the said website.

Download Routine

This Trojan takes advantage of the following software vulnerabilities to allow a remote user or malware/grayware to download files:

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

  • http://{BLOCKED}istyle.com/wap/include/2929.exe

It saves the files it downloads using the following names:

  • %User Profile%\Application Data\b.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Trend Micro detects the dowloaded file as:

  • TROJ_DROPPR.FNZ

Solution


Minimum scan engine: 8.900
First VSAPI Pattern File: 6.935.00
First VSAPI Pattern Release Date: 19 Mar 2010
VSAPI OPR Pattern Version: 7.521.00
VSAPI OPR Pattern Release Date: 07 Oct 2010

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

Close all opened browser windows

Step 3

Remove malware files dropped/downloaded by JS_COSMU.A

Step 4

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