Threat Description



Aliases: Bifrose.EE, Bifrose,
Category: Malware
Type: Backdoor
Platform: W32


Bifrose is a stealthy backdoor that allows remote access to infected machine. It is usually installed to system by a trojan dropper.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.


Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Technical Details

Installation to system

When run, the backdoor copies itself under %SysDir% directory using the name 'syspare.exe'. It installs the following registry keys to make sure it will be executed next time the system is started:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]  "syspare.exe" = "syspare.exe"  [HKLM\Software\Microsoft\Active Setup\Installed Components\{9B71D88C-C598-4935-C5D1-43AA4DB90836}]  "stubpath.exe" = "syspare.exe"   

The backdoor also creates the following registry key for storing information:


After the installation, Bifrose tries to locate a running web browser and inject code into it. The injected code is the actual backdoor. The backdoor starts to communicate with the server part using specially crafted HTTP queries. The server can instruct the backdoor to execute the following actions:

Basic file operations (copy, delete, rename, find, execute)  Download/upload files  Process operations (list, kill)  Registry operations (create/delete keys/values)  Create screenshots of the desktop  


Detection Type: PC
Database: 2005-09-24_01

Technical Details:Jarkko Turkulainen; October 4th, 2005


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