Threat Encyclopedia

JS_DLOADER.BXR

Malware type: JavaScript

Aliases: Exploit-CreateTxtRng !! (McAfee), TR/Expl.HTML.CreateRange.A (Avira), Exp/TxtRng-A (Sophos),

In the wild: Yes

Destructive: No

Language: English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Medium

Distribution potential:

Medium

Description: 

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

JS_DLOADER.BXR Behavior Diagram

Malware Overview

This malicious JavaScript is takes advantage of a vulnerability in the createTextRange Method call process in Internet Explorer. A text range enables a user to modify text within an object. This JavaScript causes an error in the mentioned text range, which is applied to a radio button control, allowing malicious Web sites to consume a large amount of an affected system's memory and this JavaScript to execute arbitrary codes on the machine.

To read more about the vulnerability, please refer to the Microsoft Security Bulletin found here.

This JavaScript also downloads and executes a file detected by Trend Micro as WORM_SPYBOT.DC from http://www.tex{BLOCKED}um.se/updater.exe.

For additional information about this threat, see:

Description created: Mar. 24, 2006 5:02:06 PM GMT -0800


TECHNICAL DETAILS


File type: Script

Size of malware: 5,362 Bytes

Initial samples received on: Mar 24, 2006

Vulnerability used:  (MS06-013) Cumulative Security Update for Internet Explorer (912812)

Related toWORM_SPYBOT.DC

Payload 1: Downloads files

Payload 2: Consumes a large amount of system memory

Details:

This malicious JavaScript is a zero-day exploit that takes advantage of a vulnerability in the createTextRange Method call process in Internet Explorer. A text range enables a user to modify text within an object. This JavaScript causes an error in the mentioned text range, which is applied to a radio button control, allowing malicious Web sites to consume a large amount of an affected system's memory and this JavaScript to execute arbitrary codes on the machine.

To read more about the vulnerability, please refer to the Microsoft Security Bulletin found here.

This JavaScript also downloads and executes a file detected by Trend Micro as WORM_SPYBOT.DC from http://www.tex{BLOCKED}um.se/updater.exe.

This JavaScript affects Internet Explorer 6.0 and Internet Explorer 7 Beta 2 Preview (January Edition) running on Windows 95, 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Gus Vincent T. Dato

Revision History:

 

Apr 12, 2006 - Modified Virus Report

SOLUTION


Minimum scan engine version needed: 7.500

Pattern file needed: 3.284.05

Pattern release date: Mar 24, 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:

Note: To fully remove all associated malware, perform the clean solution for WORM_SPYBOT.DC.

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_DLOADER.BXR. 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 Patches

This malware exploits known a 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.




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