TROJ_BREDLAB.AVM

 Analysis by: Michael Cabel

 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 uses social engineering methods to lure users into performing certain actions that may, directly or indirectly, cause malicious routines to be performed. Specifically, it makes use of interesting names as file names of the attached file in spammed email messages to lure users into clicking on them.

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

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It executes then deletes itself afterward.

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

  TECHNICAL DETAILS

File Size:

20,992 bytes

File Type:

PE

Memory Resident:

No

Initial Samples Received Date:

08 Aug 2010

Payload:

Downloads files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Trojan executes then deletes itself afterward.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}.{BLOCKED}.74.161/mrmun_sgjlgdsjrthrtwg.exe
  • http://{BLOCKED}.{BLOCKED}.112.3/bat.exe

It saves the files it downloads using the following names:

  • %Application Data%\{random file name}.exe
  • %Temp%\_ex-08.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)

Trend Micro detects the dowloaded file as:

  • TROJ_FAKEAV.ZZS
  • TROJ_BREDOLAB.WV

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

FIRST VSAPI PATTERN FILE:

7.348.01

FIRST VSAPI PATTERN DATE:

29 Jul 2010

VSAPI OPR PATTERN File:

7.373.00

VSAPI OPR PATTERN Date:

09 Aug 2010

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_BREDLAB.AVM

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_BREDLAB.AVM. 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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