BKDR_BYYA.DUKKS

October 09, 2012
 Analysis by: Roland Marco Dela Paz
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • 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 opens a hidden Internet Explorer window. It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

40,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Jul 2011

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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{343F94C0-7BF8-95A0-9892-DE53539F2AF8}
StubPath = "%System%:msfultcomen.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

Backdoor Routine

This backdoor opens a hidden Internet Explorer window.

It connects to the following websites to send and receive information:

  • {BLOCKED}i.{BLOCKED}s.com

As of this writing, the said sites are inaccessible.

NOTES:
Upon execution, this backdoor copies itself to an alternate data stream (ADS) as the following:

  • %System%:msfultcomen.exe

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

8.271.00

VSAPI OPR PATTERN Date:

06 Jul 2011

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 key

[ 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
    • Local AppWizard-Generated Applications
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {343F94C0-7BF8-95A0-9892-DE53539F2AF8}

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_BYYA.DUKKS. 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.

NOTES:

Delete the ADS file

To delete the ADS file this malware created:

1. Open a command prompt window. Click Start>Run, type CMD, and then press the Enter.

2. At the command prompt, type the following: echo null %System%:msfultcomen.exe

(Note: %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. %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.)

3. Close the command prompt window.


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