Win32/Bifrose [Threat Name] go to Threat

Win32/Bifrose.NEL [Threat Variant Name]

Category trojan
Size 111616 B
Aliases Backdoor:Win32/Bifrose.AE (Microsoft)
  Infostealer (Symantec)
  Win32:Midgare-WV (Avast)
  Trojan.Dropper.SAG (BitDefender)
Short description

Win32/Bifrose.NEL installs a backdoor that can be controlled remotely. The file is run-time compressed using IExpress, UPX .


When executed, the trojan creates the following files:

  • %temp%\­IXP%random%.TMP\­server.exe (32669 B, Win32/Bifrose.NEL)
  • %programfiles%\­Bifrost\­server.exe (32669 B, Win32/Bifrose.NEL)

The following Registry entry is set:

  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Microsoft\­Active Setup\­Installed Components\­{9D71D88C-C598-4935-C5D1-43AA4db90836}]
    • "stubpath" = "%programfiles%\­Bifrost\­server.exe s"

This causes the trojan to be executed on every system start.

The following Registry entries are created:

    • "nck" = "%variable1%"
    • "klg" = 0
    • "nck" = "%variable1%"

The trojan may set the following Registry entries:

    • "delay" = "%variable2%"
    • "plg1" = "%variable3%"
    • "tor" = "%variable4%

A string with variable content is used instead of %variable1-4% .

The trojan may delete the following Registry entries:

  • [HKEY_CURRENT_USER\­SOFTWARE\­Microsoft\­Active Setup\­Installed Components\­{9D71D88C-C598-4935-C5D1-43AA4db90836}]

The trojan launches the following processes:

  • %windir%\­explorer.exe
  • %defaultbrowser%

The trojan creates and runs a new thread with its own code within these running processes.

Information stealing

Win32/Bifrose.NEL is a trojan that steals sensitive information.

The trojan collects the following information:

  • computer IP address
  • computer name
  • user name
  • volume serial number
  • the path to specific folders
  • information about the operating system and system settings
  • current screen resolution

The trojan attempts to send gathered information to a remote machine.

Other information

The trojan serves as a backdoor. It can be controlled remotely.

The trojan acquires data and commands from a remote computer or the Internet.

The trojan contains a URL address. The TCP protocol is used.

It can execute the following operations:

  • download files from a remote computer and/or the Internet
  • run executable files
  • send files to a remote computer
  • send the list of running processes to a remote computer
  • send the list of disk devices and their type to a remote computer
  • send the list of files on a specific drive to a remote computer
  • create folders
  • delete folders
  • move files
  • terminate running processes
  • create Registry entries
  • show/hide application windows
  • log keystrokes
  • uninstall itself
  • stop itself for a certain time period
  • capture screenshots
  • capture webcam video/voice
  • execute shell commands

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