Threat Encyclopedia

JS_YAMANNER.A

Malware type: JavaScript

Aliases: JS/Yamann-A (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 98, ME, NT, 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Infection Channel 1 : Propagates via email


Description: 

To get a one-glance comprehensive view of the behavior of this malicious JavaScript, refer to the Behavior Diagram shown below.

JS_YAMANNER.A Behavior Diagram

Malware Overview

This malicious JavaScript arrives on a system as an embedded file in a Yahoo! email message. When a user opens the said email message, this malicious JavaScript automatically executes.

It takes advantage of a vulnerability found in Yahoo! Web-based email service in order to send copies of itself to an affected user's Yahoo! contacts. It gathers email addresses from Yahoo! email folders. The said action further spreads this malware.

It connects to the URL http://www.a{BLOCKED}et to send a list of email addresses it gathers. This routine exposes private information to possible attackers.

For additional information about this threat, see:

Description created: Jun. 12, 2006 3:29:26 PM GMT -0800


TECHNICAL DETAILS


File type: Script

Size of malware: Varies

Initial samples received on: Jun 12, 2006

Payload 1: Steals information

Details:

This malicious JavaScript arrives on a system as an embedded file in a Yahoo! email message. When a user opens the said email message with the following details, this malicious JavaScript automatically executes:

From: {Random}

Subject: New Graphic Site

Message body: (any of the following)
• Note: forwarded message attached
• this is test

Once the email message is opened, it takes advantage of a vulnerability found in the Yahoo! Web-based email service and runs this malicious JavaScript. It sends a copy of itself to an affected user's Yahoo! contacts. It gathers email addresses from Yahoo! email folders, targeting addresses with @yahoo.com and @yahoogroups.com domains.

It connects to the URL http://www.a{BLOCKED}et to send a list of email addresses it gathers.

This malicious JavaScript runs on Windows 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Michelle Perona

Revision History:

 
Jun 13, 2006 - Modified from JS_YAMANER.A

SOLUTION


Minimum scan engine version needed: 7.500

Pattern file needed: 3.498.02

Pattern release date: Jun 13, 2006


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:

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected computers.

Users running other Windows versions can proceed with the succeeding solution set(s).

Running Trend Micro Antivirus

If you are currently running in safe mode, please restart your computer normally before performing the following solution.

Scan your computer with Trend Micro antivirus and delete files detected as JS_YAMANNER.A. To do this, Trend Micro customers must download the latest virus pattern file and scan their computer. Other Internet users can use HouseCall, the Trend Micro online virus scanner.




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