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TROJ_BREDLAB.AIT

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

TrojanDownloader:Win32/Waledac.C (Microsoft); Spam-Mailbot.m (McAfee); Backdoor.Win32.Bredolab.gii (Kaspersky); Trojan.Win32.Rimecud.a (GFI-Sunbelt); W32/Krap.X!tr (Fortinet); Win32/TrojanDownloader.Bredolab.AN trojan (Nod32); Bck/Bredolab.AZ (Panda)

 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

This Trojan arrives as attachment to mass-mailed email messages.

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

  TECHNICAL DETAILS

File Size:

27,136 bytes

File Type:

PE

Memory Resident:

No

Initial Samples Received Date:

13 Aug 2010

Arrival Details

This Trojan arrives as attachment to mass-mailed email messages.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}.{BLOCKED}.74.161/mrmun_sgjlgdsjrthrtwg.exe
  • http://{BLOCKED}.{BLOCKED}.191.111/bat.exe

It saves the files it downloads using the following names:

  • %Application Data%\{random file name}.exe
  • %Temp%\_ex-{random number}.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.SMDM
  • TROJ_FAKEAV.SMJR

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 OPR PATTERN File:

7.381.00

VSAPI OPR PATTERN Date:

14 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.AIT

Step 3

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