Threat Encyclopedia

JS_DLOADER.AZZ

Malware type: JavaScript

Aliases: Exploit.JS.CVE-2005-1790.d (Kaspersky), Downloader (Symantec), Exp/JS.CVE2005-1790 (Avira), Mal/JSShell-B (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, ME, NT, 2000, XP, and Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Medium

Description: 

This JavaScript malware may be opened using Internet Explorer (IE) while a user visits different Web sites. It uses a known vulnerability in IE, which results in the download and execution of files without the knowledge of the user.

More information about this vulnerability can be found in this page:

It attempts to download a file from the site http://82.1{BLOCKED}.166.2/statpath5/outxxx.jpg.

The downloaded file is detected by Trend Micro as TROJ_SMALL.AMI.

For additional information about this threat, see:

Description created: Dec. 10, 2005 12:06:43 AM GMT -0800


TECHNICAL DETAILS


File type: Script

Memory resident:  No

Size of malware: Varies

Initial samples received on: Dec 8, 2005

Vulnerability used:  (MS05-054) Cumulative Security Update for Internet Explorer (905915)

Related toTROJ_SMALL.AMI

Payload 1: Downloads files

Details:

This JavaScript malware may be opened using Internet Explorer (IE) while a user visits different Web sites. It uses a known vulnerability in IE, which results in the download and execution of files without the knowledge of the user.

More information about this vulnerability can be found in this page:

It attempts to download a file from the site http://82.1{BLOCKED}.166.2/statpath5/outxxx.jpg.

This JavaScript malware is usually embedded in HTML documents and is encoded using Unescape Utility. It affects systems running on Windows 95, 98, ME, NT, 2000, XP, and Server 2003

The downloaded file is detected by Trend Micro as TROJ_SMALL.AMI.

This JavaScript program runs on Windows 95, 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Carlo Panganiban

Updated By: Jay-R Tan

Revision History:

First pattern file version: 2.994.07
First pattern file release date: Dec 10, 2005
 
Dec 10, 2005 - Modified Virus Report
Dec 20, 2005 � Insertion of Reference to Microsoft Security Bulletin MS05-054

SOLUTION


Minimum scan engine version needed: 7.000

Pattern file needed: 3.101.00

Pattern release date: Dec 12, 2005


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:

Note: To fully remove all associated malware, perform the clean solution for TROJ_SMALL.AMI.

Important Windows ME/XP Cleaning Instructions

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

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

Running Trend Micro Antivirus

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

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

Applying Patches

This malware exploits known vulnerabilities in Internet Explorer. Download and install the fix patch supplied by Microsoft. Refrain from using this product until the appropriate patch has been installed. Trend Micro advises users to download critical patches upon release by vendors.




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