BKDR_BIFROSE.DVU

October 08, 2012
 Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 98, ME, NT, 2000, XP, Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor opens a hidden Internet Explorer window.

It attempts to access certain websites. However, the websites are inaccessible as of this writing.

  TECHNICAL DETAILS

File Size:

41 bytes

File Type:

EXE

Memory Resident:

Yes

Installation

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

  • %system%\wmirsvs.exe

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
wmirsvscv = %system%\wmirsvs.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{113DF7EC-651B-76AA-AD69-4005FE080DE8}
stubpath = %system%\wmirsvs.exe

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\NKav
klg = 0

HKEY_LOCAL_MACHINE\SOFTWARE\NKav
nck = {hex values}

Backdoor Routine

This backdoor opens a hidden Internet Explorer window.

Other Details

This backdoor attempts to access certain websites. However, the websites are inaccessible as of this writing.

It connects to the following possibly malicious URL:

  • 220.130.135.182

  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

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.

 HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run 
wmirsvscv = %system%\wmirsvs.exe


HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{113DF7EC-651B-76AA-AD69-4005FE080DE8} 
stubpath = %system%\wmirsvs.exe

Step 4

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.

HKEY_CURRENT_USER\Software\NKav
klg = 0

HKEY_LOCAL_MACHINE\SOFTWARE\NKav
nck = {hex values}

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_BIFROSE.DVU. 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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