Analysis by: Roland Marco Dela Paz
ALIASES:

RTF:CVE-2010-3333 [Expl] (Avast); Exp/20103333-A (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email

This Trojan arrives as an attachment to email messages purportedly promoting Tibetan culture. It drops a file that is a backdoor and is infected by a file infector.

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

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

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 1,780,792 bytes
File Type: RTF
Initial Samples Received Date: 06 Apr 2012
Payload: Drops files

Arrival Details

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

Installation

This Trojan drops the following non-malicious file:

  • %User Temp%\document.doc

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Dropping Routine

This Trojan drops the following files:

It takes advantage of the following software vulnerabilities to drop malicious files:

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

NOTES:

Upon execution, it opens its dropped non-malicious .DOC file %User Temp%\document.doc in order to hide its malicious routines from the user.

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)

The following dropped malicious file is also found to be infected by PE_SALITY.AC:

  • %User Temp%\svchost.exe - detected as BKDR_RILER.SVR

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)

Consequently, routines of both BKDR_RILER.SVR and PE_SALITY.AC are executed on the affected system.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.890.09
FIRST VSAPI PATTERN DATE: 06 Apr 2012
VSAPI OPR PATTERN File: 8.893.00
VSAPI OPR PATTERN Date: 08 Apr 2012

Step 1

For Windows XP and Windows Server 2003 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_ARTIEF.EDX


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