Analysis by: Michael Cabel
ALIASES:

Microsoft: Adware:Win32/Agent.C; Symantec : Trojan.Dropper

 PLATFORM:

Windows 2000, XP, 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 may be unknowingly downloaded by a user while visiting malicious websites. It may be manually installed by a user.

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: 1,271,809 bytes
File Type: PE
Memory Resident: No
Initial Samples Received Date: 09 Feb 2011

Arrival Details

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

It may be manually installed by a user.

Installation

This Trojan drops the following non-malicious files:

  • %System%\X-masTree.Scr
  • %User Temp%\FlashListsX-MAST~1.SCR\X-mas Tree.swf
  • %Common Startup%\Programs\X-masTree\Uninstall X-masTree.lnk

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %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.. %Common Startup% is the system's shared Startup folder, which is usually C:\Windows\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\All Users\Programs\Startup on Windows NT, and C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003.)

It creates the following folders:

  • %User Temp%\FlashListsX-MAST~1.SCR
  • %Common Startup%\Programs\X-masTree

(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.. %Common Startup% is the system's shared Startup folder, which is usually C:\Windows\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\All Users\Programs\Startup on Windows NT, and C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\Ofb1.exe - detected as ADW_WEBSEARCH.CI
  • %User Temp%\OFoxInstaller_s.exe - detected as ADW_OWLFORCE.D
  • %User Temp%\OpenIE_S.exe - detected as ADW_OWLFORCE

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

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.827.80
VSAPI PATTERN Date: 09 Feb 2011
VSAPI PATTERN Date: 2/9/2011 12:00:00 AM

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_DROPPER.XXX

Step 3

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
%User Temp%\FlashListsX-MAST~1.SCR
%Common Startup%\Programs\X-masTree

Step 4

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. %System%\X-masTree.Scr

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.XXX. 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.


Did this description help? Tell us how we did.