Threat Encyclopedia

EXPL_TXTRANGE.A

Malware type: Exploit

Aliases: Exploit.VBS.Phel.aa (Kaspersky), Hacktool.IE.Exploit (Symantec), EXP/CVE-2006-1359 (Avira), Exp/Phel-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:

Medium

Description: 

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

EXPL_TXTRANGE.A Behavior Diagram

Malware Overview

This is Trend Micro's detection for a zero-day exploit that takes advantage of a vulnerability in the createTextRange Method call process in Internet Explorer. Using the aforementioned method enables a user to create a text range within an object. The said vulnerability is discussed in detail in the following Microsoft Web page:

This exploit 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 to execute arbitrary codes on the system. It can also download and execute malicious codes on the system.

Zero-day exploits are termed as such because the unpatched vulnerability and its corresponding exploit code are released within the same day. This poses a threat in which a lot of computers may be affected due to the availability of exploit code, and the fact that the vendor has not been given enough time to patch it.

One malicious JavaScript that uses this exploit is detected by Trend Micro as JS_DLOADER.BXR.

For additional information about this threat, see:

Description created: Mar. 25, 2006 2:07:24 PM GMT -0800


TECHNICAL DETAILS


File type: Script

Memory resident:  No

Size of malware: Varies

Initial samples received on: Mar 25, 2006

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

Related toJS_DLOADER.BXR

Payload 1: Compromises system security

Payload 2: Consumes a large amount of system memory

Details:

This is Trend Micro's detection for a zero-day exploit that takes advantage of a vulnerability in the createTextRange Method call process in Internet Explorer. Using the aforementioned method enables a user to create a text range within an object. The said vulnerability is discussed in detail in the following Microsoft Web page:

This exploit 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 to execute arbitrary codes on the system. It can also download and execute malicious codes on the system.

Zero-day exploits are termed as such because the unpatched vulnerability and its corresponding exploit code are released within the same day. This poses a threat in which a lot of computers may be affected due to the availability of exploit code, and the fact that the vendor has not been given enough time to patch it.

One malicious JavaScript that uses this exploit is detected by Trend Micro as JS_DLOADER.BXR.

This exploit affects Internet Explorer 6.0 and Internet Explorer 7.0 Beta 2 (January Edition) running on Windows 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Arman Castro Catacutan


SOLUTION


Minimum scan engine version needed: 7.500

Pattern file needed: 3.292.03

Pattern release date: Mar 28, 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 JS_DLOADER.BXR.

Disabling Active Scripting Support

The following article provides the steps to disable active scripting in Internet Explorer which, when enabled, may allow remote code execution:

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 EXPL_TXTRANGE.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.

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.




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