Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

It displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.

  TECHNICAL DETAILS

File Size: 432,640 bytes
File Type: PE
Memory Resident: No
Initial Samples Received Date: 05 Jul 2010
Payload: Drops files

Installation

This Trojan drops the following copies of itself into the affected system:

  • %User Temp%\AUTMGR32.EXE
  • %User Temp%\topwesitjh

(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 drops the following file(s)/component(s):

  • %User Temp%\mschrt20ex.dll - detected as same malware

(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.)

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\secfile\shell\
open\command
@ = "%User Temp%\AUTMGR32.EXE" /START "%1" %*

HKEY_CLASSES_ROOT\.exe\shell\
open\command
@ = "%User Temp%\AUTMGR32.EXE" /START "%1" %*

HKEY_CURRENT_USER\Software\Classes\
.exe\shell\open\
command
@ = "%User Temp%\AUTMGR32.EXE" /START "%1" %*

HKEY_CURRENT_USER\Software\Classes\
secfile\shell\open\
command
@ = "%User Temp%\AUTMGR32.EXE" /START "%1" %*

It adds the following registry entries to disable the Task Manager:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
DisableTaskMgr = 1

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\wscsvc32.exe - detected by Trend Micro as TROJ_FAKEAV.SMEV

(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.)

Rogue Antivirus Routine

This Trojan displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 07.288.13
VSAPI PATTERN Date: 06 Jul 2010
VSAPI PATTERN Date: 7/6/2010 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_FAKEAV.CLC

    • TROJ_FAKEAV.SMEV

Step 3

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CLASSES_ROOT\\.exe
    • From: @=secfile
      To: exefile

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CLASSES_ROOT\\secfile\\shell\\open\\command
    • @=%User Temp%\\AUTMGR32.EXE /START %1 %*
  • In HKEY_CLASSES_ROOT\\.exe\\shell\\open\\command
    • @=%User Temp%\\AUTMGR32.EXE /START %1 %*
  • In HKEY_CURRENT_USER\\Software\\Classes\\.exe\\shell\\open\\command
    • @=%User Temp%\\AUTMGR32.EXE /START %1 %*
  • In HKEY_CURRENT_USER\\Software\\Classes\\secfile\\shell\\open\\command
    • @=%User Temp%\\AUTMGR32.EXE /START %1 %*
  • In HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System
    • DisableTaskMgr=1
  • In HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\policies\\system
    • DisableTaskMgr=1

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.CLC. 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.


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