Analysis by: Karl Dominguez
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan has two embedded .SWF files in its body that it uses to exploit CVE-2011-0611. The two .SWF files are detected as SWF_EXPLOIT.WS.

If exploit is successful, it drops files.

This Trojan arrives as an attachment to email messages spammed by other malware/grayware/spyware or malicious users. It may be unknowingly downloaded by a user while visiting malicious websites.

It exploits a vulnerability identified as in a zero-day attack.

  TECHNICAL DETAILS

File Size: 82,558 bytes
File Type: DOC
Initial Samples Received Date: 22 Apr 2011
Payload: Drops files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware/spyware or malicious users.

It may be unknowingly downloaded by a user while visiting malicious websites.

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • hwp.exe

Other Details

This Trojan exploits a zero-day vulnerability. More information on the said vulnerability can be found in the following pages:

  • CVE-2011-0611
  • http://www.adobe.com/support/security/bulletins/apsb11-07.html

NOTES:

This .DOC file has two embedded .SWF files in its body that it uses to exploit CVE-2011-0611. The two .SWF files are detected as SWF_EXPLOIT.WS.

If exploit is successful, it drops the following files:

  • %User Temp%\svchost.exe - TROJ_DLOADR.WSA
  • %User Temp%\AAAA - non-malicious .DOC file that the malware opens to hide its malicious routines.

It overwrites itself with the non-malicious document file %User Temp%\AAAA and opens this to trick users into thinking that it is non-malicious.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.988.04
FIRST VSAPI PATTERN DATE: 19 Apr 2011

Step 1

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by TROJ_MDROP.SW

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_MDROP.SW If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 4

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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