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TROJ_ACTIFF.B

November 07, 2013
 Analysis by: Alvin Bacani
 ALIASES:

Exploit:Win32/CVE-2013-3906 (Microsoft); Trojan.Hantiff (Symantec); Exploit-CVE2013-3906 (McAfee)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This malware is involved in the targeted attacks that took advantage of an unpatched Microsoft Office vulnerability, namely CVE-2013-3906, on November 2013. Victims of this malware may find the security of their systems compromised.

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

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

309,846 bytes

File Type:

DOCX

Initial Samples Received Date:

06 Nov 2013

Payload:

Downloads files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Download Routine

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

  • CVE-2013-3906

After successfully exploiting the said vulnerability, this malware connects to the following URLs to possibly download other malicious files:

  • http://{BLOCKED}net.com/bruce/winword.exe
  • http://{BLOCKED}net.com/ralph_3/winword.exe

It saves the files it downloads using the following names:

  • %User Temp%\winword.exe

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

More information on this vulnerability can be found below:

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

10.394.05

FIRST VSAPI PATTERN DATE:

06 Nov 2013

VSAPI OPR PATTERN File:

10.395.00

VSAPI OPR PATTERN Date:

06 Nov 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Search and delete this file

[ Learn More ]
There may be some 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.  
  • %User Temp%\winword.exe

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_ACTIFF.B. 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.

NOTES:

Download Fix-it Tool released by vendor to temporarily address the issue:


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