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Threat Encyclopedia

JS_DLOAD.MD

Malware type: JavaScript

Aliases: Exploit.JS.Agent.yq (Kaspersky), Exploit-XMLhttp.d.gen (McAfee), Bloodhound.Exploit.219 (Symantec), JS/Bofra.A.1 (Avira), Exploit:JS/Mult.AI (Microsoft)

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 2000 (SP4), XP, Server 2003, Vista, Server 2008

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Medium

Distribution potential:

Low

Description: 

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

JS_DLOAD.MD Behavior Diagram

Malware Overview

This malicious JavaScript may be hosted on a Web site and run when a user accesses the said Web site.

It takes advantage of a vulnerability in several versions of Internet Explorer.

More information on the said vulnerability can be found on the following link:

Once it successfully exploits the vulnerability, it accesses various URLs to download malicious files, including RTKT_BUREY.C. As a result, malicious routines of the downloaded files may be exhibited on the affected system.

For additional information about this threat, see:

Description created: Dec. 10, 2008 12:05:43 AM GMT -0800


TECHNICAL DETAILS


File type: Script

Size of malware: Varies

Initial samples received on: Dec 10, 2008

Vulnerability used:  (MS08-078) Security Update for Internet Explorer (960714)

Payload 1: Downloads files

Details:

This malicious JavaScript may be hosted on a Web site and run when a user accesses the said Web site. It may also be downloaded from the following URL:

    http://{BLOCKED}7.cn/{any number from 1 to 99}/ie7.htm

It takes advantage of a vulnerability in several versions of Internet Explorer. The exploit method used is a Heap Spray on SDHTML. It executes a script that checks the version of Internet Explorer. It then executes a shellcode that aims to overflow the heap allocated.

More information on the said vulnerability can be found on the following link:

Once it successfully exploits the vulnerability, it accesses any of the following URLs to download malicious files:

  • http://{BLOCKED}u.com/iiee/explore.exe - detected as RTKT_BUREY.C
  • http://{BLOCKED}yyy.cn/1.exe - detected as TROJ_DROPPER.EYC
  • http://www.{BLOCKED}c.cn/down/ko.exe - detected as TROJ_SMALL.IYS
  • http://www.{BLOCKED}stemudpata.com/ieupdate.exe - inaccessible as of this writing

As a result, malicious routines of the downloaded files may be exhibited on the affected system.

Moreover, the vulnerable browser may crash when accessing a site that contains the specially-crafted JavaScript code.

This malicious JavaScript runs on Windows 2000 (SP4), XP, Server 2003, Vista, and Server 2008 with Internet Explorer versions 5.01 SP4 to 8 Beta 2 installed.

Analysis By: Kathleen Mae Notario

Revision History:

 
Dec 11, 2008 - JS_AGENT.CSZZ renamed to JS_DLOAD.MD in CPR 5.706.04
Dec 12, 2008 - Modified Malware Report

SOLUTION


Minimum scan engine version needed: 8.700

Pattern file needed: 5.701.00

Pattern release date: Dec 10, 2008


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: Close all instances of Internet Explorer before proceeding with the following solution.)

Important Windows XP Cleaning Instructions

Users running Windows 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_DLOAD.MD, TROJ_DROPPER.EYC and TROJ_SMALL.IYS. 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.

Applying Patch

This malware exploits a known vulnerability 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.


Note: To prevent your system from being infected by this malware, you may refer to the following workarounds:

  • Set Internet and Local intranet security zone settings to "High" to enable prompts before running ActiveX Controls and Active Scripting in these zones
  • Configure Internet Explorer to prompt before running Active Scripting or to disable Active Scripting in the Internet and Local intranet security zone
  • Enable DEP for Internet Explorer 7
  • Use ACL to disable OLEDB32.DLL.
  • Unregister OLEDB32.DLL.
  • Disable Data Binding support in Internet Explorer 8



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