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BKDR_TURKOJAN.C

November 14, 2012
 Analysis by: Mark Joseph Manahan
 ALIASES:

VirTool:Win32/VBInject.gen!AC (Microsoft), Backdoor-DZP (McAfee), a variant of Win32/Injector.OH trojan (Eset), Backdoor.Bifrose (Symantec)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

258,048 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Nov 2012

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor drops the following copies of itself into the affected system and executes them:

  • %Windows%\mstwain32.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It drops and executes the following files:

  • %Windows%\cmsetac.dll
  • %Windows%\ntdtcstp.dll

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
mstwain32 = "%Windows%\mstwain32.exe"

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}ri.no-ip.biz:15963

Dropping Routine

This backdoor drops the following file(s), which it uses for its keylogging routine:

  • %Windows%\KB8888239.log

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

  SOLUTION

Minimum Scan Engine:

9.300

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

Restart in Safe Mode

[ Learn More ]

Step 3

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
    • mstwain32 = "%Windows%\mstwain32.exe"

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.
  • %Windows%\KB8888239.log
  • %Windows%\cmsetac.dll
  • %Windows%\ntdtcstp.dll

Step 5

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