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TROJ_HWPEXPL.VTG

October 09, 2012
 Analysis by: Sabrina Lei Sioting
 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:

Dropped by other malware, Downloaded from the Internet


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 takes advantage of software vulnerabilities in certain software to drop malicious files. It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

  TECHNICAL DETAILS

File Size:

438,853 bytes

File Type:

Other

Memory Resident:

No

Initial Samples Received Date:

18 Jun 2012

Payload:

Drops 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.

Installation

This Trojan drops the following non-malicious files:

  • %User Temp%\haha.hwp
  • %User Temp%\IMP00000{random}.HWP

(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:

  • %User Temp%\{random}.tmp - detected as TROJ_DROPPER.SLS

(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.)

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

  • Hancom Office

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

NOTES:

Upon execution, this Trojan opens its dropped non-malicious .HWP file %User Temp%\haha.hwp in order to hide its malicious routines from the user.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.202.05

FIRST VSAPI PATTERN DATE:

18 Jun 2012

VSAPI OPR PATTERN File:

9.203.00

VSAPI OPR PATTERN Date:

18 Jun 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_HWPEXPL.VTG

    TROJ_DROPPER.SLS

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. haha.hwp
IMP00000{random}.HWP

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_HWPEXPL.VTG. 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.   http://www.hancom.com/downLoad.downPU.do?mcd=001


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