Analysis by: Kathleen Notario
 PLATFORM:

Windows 98, ME, NT, 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 may be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

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

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 33,280 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 14 Jul 2010
Payload: Drops files, Downloads files

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

It may be dropped by other malware.

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

Installation

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

  • %User Startup%\srvklw32.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

It injects itself into the following processes running in the affected system's memory:

  • svchost.exe

Dropping Routine

This Trojan drops the following files:

  • C:\Documents and Settings\NetworkService\Application Data\hwzypv.dat
  • %Application Data%\avdrn.dat
  • %System%\fjhdyfhsn.bat - detected as BAT_KILLFILE.AK

(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.. %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.)

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}g.ru/new/controller.php?action=bot&entity_list=&first={random}&rnd={random}&uid=1&guid={random}
  • http://{BLOCKED}.{BLOCKED}.203.114/mybackup20.rar
  • http://{BLOCKED}.{BLOCKED}.82.186/mybackup20.rar
  • http://{BLOCKED}.{BLOCKED}.237.163:8080/images/bot.bin - detected as RTKT_BUBNIX.A
  • http://{BLOCKED}.{BLOCKED}.177.87:8080/images/bot.bin - detected as RTKT_BUBNIX.A
  • http://{BLOCKED}.{BLOCKED}.50.135:8080/images/bot.bin - detected as RTKT_BUBNIX.A

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

Other Details

This Trojan deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 8.900

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_BREDOLAB.EM

    • BAT_KILLFILE.AK
    • RTKT_BUBNIX.A

Step 3

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_BREDOLAB.EM. 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.

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.

  • C:\Documents and Settings\NetworkService\Application Data\hwzypv.dat
  • %Application Data%\avdrn.dat


Did this description help? Tell us how we did.