ALIASES:

Backdoor:Win32/Bifrose (Microsoft); BackDoor-CEP.svr (McAfee); Trojan Horse (Symantec); Trojan.Win32.Agent.bcn, Backdoor.Win32.Bifrose.aci, Backdoor.Win32.Bifrose.adr (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Backdoor:W32/Bifrose.gen!A (FSecure)

 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.

  TECHNICAL DETAILS

File Size: 29,053 bytes
File Type: EXE
Initial Samples Received Date: 01 Oct 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.

Installation

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

  • %Windows%\messengner\msn.exe

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

It creates the following folders:

  • %Windows%\messengner

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

Other System Modifications

This backdoor deletes the following files:

  • %Windows%\messengner\msn.exe

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

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A47B24A1-E242-AB90-1800-8EDE1230CFEC}

HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost

HKEY_CURRENT_USER\SOFTWARE\Bifrost

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\MediaResources\msvideo

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A47B24A1-E242-AB90-1800-8EDE1230CFEC}
stubpath = "%Windows%\messengner\msn.exe s"

HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost
nck = {random values}

HKEY_CURRENT_USER\Software\Bifrost
klg = {random values}

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {A47B24A1-E242-AB90-1800-8EDE1230CFEC}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • Bifrost
  • In HKEY_CURRENT_USER\SOFTWARE
    • Bifrost
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MediaResources
    • msvideo

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A47B24A1-E242-AB90-1800-8EDE1230CFEC}
    • stubpath="%Windows%\messengner\msn.exe s"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost
    • nck={random values}
  • In HKEY_CURRENT_USER\Software\Bifrost
    • klg={random values}

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %Windows%\messengner

Step 5

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