Analysis by: Roland Marco Dela Paz
ALIASES:

Trojan.Mdropper (Symantec); Exploit.MSWord.CVE-2010-3333.b (Kaspersky)

 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

It takes advantage of vulnerabilities in Microsoft Office that could allow remote code execution (MS10-087). After successfully exploiting the said vulnerability, it drops a file detected as BKDR_AGENT.U.

Upon execution, it opens a .DOC file in order to hide its malicious routines from the user.

This Trojan executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

Once a malware successfully exploits the said vulnerability, it causes certain actions to be done on the system.

  TECHNICAL DETAILS

File Size: Varies
File Type: Other
Memory Resident: No
Initial Samples Received Date: 16 Mar 2011
Payload: Drops files

Installation

This Trojan drops the following non-malicious file:

  • C:\word.doc

Dropping Routine

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

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

Other Details

Once a malware successfully exploits the said vulnerability, it causes the following actions to be done on the system:

  • It drops the file %User Temp%\WINWORD.EXE, which is detected as BKDR_AGENT.U.

(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.)

NOTES:
Upon execution, it opens C:\word.doc in order to hide its malicious routines from the user.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 7.907.00
VSAPI OPR PATTERN Date: 16 Mar 2011

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.SMB

Step 3

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • C:\word.doc

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_ARTIEF.SMB. 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 5

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.

NOTES:


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