TROJ_FAKEAV.DFR

October 08, 2012
 Analysis by: Christopher Daniel So
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

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

It accesses websites to download files. This action allows this malware to possibly add other malware on the affected computer. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

471,296 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Sep 2010

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_CRYPTIC.BK

Installation

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

  • %User Temp%\dfrgsnapnt.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.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dfrgsnapnt.exe = "%User Temp%\dfrgsnapnt.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\wscsvc32.exe - detected 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.)

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

Download Routine

This Trojan accesses websites to download the following files:

  • http://{BLOCKED}ulltro.com/any3/5-direct.ex

Trend Micro detects the dowloaded file as:

  • TROJ_FAKEAV.SMEY

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

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.506.01

VSAPI PATTERN Date:

01 Oct 2010

VSAPI PATTERN Date:

10/1/2010 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.DFR

    TROJ_FAKEAV.SMEV
    TROJ_FAKEAV.SMEY

Step 3

Identify and terminate files detected as TROJ_FAKEAV.DFR

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dfrgsnapnt.exe=%User Temp%\dfrgsnapnt.exe

Step 5

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