Analysis by: Jeanne Jocson

ALIASES:

Backdoor.Win32.Bifrose.fpi (Kaspersky), Backdoor:Win32/Bifrose.gen!E (Microsoft)

 PLATFORM:

Windows

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

  • 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 deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 40,191 bytes
File Type: EXE
Initial Samples Received Date: 05 Aug 2016

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 a copy of itself in the following folders using different file names:

  • %User Profile%\Local Settings\wminsts.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following processes:

  • iexplorer.exe

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{UID}

HKEY_LOCAL_MACHINE\SOFTWARE\SKav

HKEY_CURRENT_USER\Software\SKav

It adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{UID}
stubpath = "%User Profile%\Local Settings\wminsts.exe s"

HKEY_LOCAL_MACHINE\SOFTWARE\SKav
nck = "{hex values}"

HKEY_CURRENT_USER\Software\SKav
klg = "00"

Other Details

This backdoor connects to the following possibly malicious URL:

  • securitybbs.{BLOCKED}s.info
  • release2002.{BLOCKED}ame.org

It deletes the initially executed copy of itself