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Trojan.Win32.BIFROST.AB

October 15, 2021
 Analysis by: Khristian Joseph Morales
 ALIASES:

W32/Bifrose.NKY!tr (FORTINET)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan 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:

164,746 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Oct 2021

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %Application Data%\addons.dat
  • %Application Data%\Bifrost\server.exe → If running on Win7
  • %Application Data%\Bifrost\logg.dat → If running on Win7
  • %Program Files%\Bifrost\server.exe → If running on WinXP
  • %Program Files%\Bifrost\logg.dat → If running on WinXP

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Bifrost
nck = {hex values}

HKEY_CURRENT_USER\Software\Bifrost
plg1 = {hex values}

HKEY_CURRENT_USER\Software\Bifrost
klg = {value}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{1D01DBE5-B57F-BA76-9003-335ABFF78D40} = %Application Data%\Bifrost\server.exe → If running on Win7

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{1D01DBE5-B57F-BA76-9003-335ABFF78D40}
stubpath = %Program Files%\Bifrost\server.exe s → If running on WinXP

Other Details

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Bifrost → If running on Win7

HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost → If running on WinXP

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{1D01DBE5-B57F-BA76-9003-335ABFF78D40} → If running on WinXP

It connects to the following possibly malicious URL:

  • simon.{BLOCKED}p.biz → If running on WinXP
  • rissim.{BLOCKED}p.biz → If running on WinXP
  • rac122.{BLOCKED}p.org → If running on WinXP

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.130.04

FIRST VSAPI PATTERN DATE:

14 Oct 2021

VSAPI OPR PATTERN File:

17.131.00

VSAPI OPR PATTERN Date:

15 Oct 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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.

 
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
    • AppData = %Application Data%
  • In HKEY_CURRENT_USER\Software\Bifrost
    • nck = {hex values}
  • In HKEY_CURRENT_USER\Software\Bifrost
    • klg = {value} 
  • In HKEY_CURRENT_USER\Software\Bifrost
    • plg1 = {hex values}
  • In HKEY_CURRENT_USER\Software\Bifrost
    • klg = {value}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {1D01DBE5-B57F-BA76-9003-335ABFF78D40} = %Application Data%\Bifrost\server.exe → If running on Win7
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{1D01DBE5-B57F-BA76-9003-335ABFF78D40}
    • stubpath = %Program Files%\Bifrost\server.exe s → If running on WinXP

Step 5

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.

  • HKEY_CURRENT_USER\Software\Bifrost → If running on Win7
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{1D01DBE5-B57F-BA76-9003-335ABFF78D40} → If running on WinXP
  • HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost → If running on WinXP

Step 6

Search and delete this file

[ Learn More ]
There may be some 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.
  • %Application Data%\addons.dat
  • %Application Data%\Bifrost\server.exe → If running on Win7
  • %Application Data%\Bifrost\logg.dat → If running on Win7
  • %Program Files%\Bifrost\server.exe → If running on WinXP
  • %Program Files%\Bifrost\logg.dat → If running on WinXP

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.BIFROST.AB. 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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