How to remove Bifrost virus system.exe

Bifrost virus system.exe

Last Updated on Thursday, 15 April 2010 09:59 Thursday, 15 April 2010 09:22

The file name system.exe has appeared in an virus analysis report. You can see it on this link

The installer is about 78 KB
It installs a component of backdoor Trojan Bifrose or BiFrost
It connects to remote hosts. It can download harmful files from the internet. A good firewall can detect harmful activities and prevent them. Some good freeware are ZoneAlarm Free Firewall, and Comodo Internet Security Free Edition (you can choose to install just the firewall from their security suite)
It infects Internet explorer browser. It has a keylogger component that it attaches with Internet Explorer. That will steal your user ID and passwords. So do not use Internet explorer until the virus is removed

It creates the files system.exe on the infected computer that you need to search and delete. You should end running processes named system.exe from Task Manager. And also remove the file's entries from windows startup.

There are several variations in the EXE file names used by this virus. I have grouped them together in BiFrost Family

Statutory Warning: It is possible that some legitimate application may be using the same name as that of the virus files. Use Windows Defender or SysInternal Process Explorer to differentiate between them.

Using System Restore

If you know the duration since your computer is infected, you can try to restore your computer at a prior date, that will be an easy way to undo the changes done by the virus

Using system restore in windows XP

Using system restore in windows Vista

Boot in safe mode

Sometimes you can not delete a file. You should boot in safe mode and then try to delete it.

How to boot in safe in windows XP

How to boot in safe mode in windows Vista

View Hidden Files

You need to enable to view hidden files and folders before searching.

How to Enable to View Hidden Files and Folders in Windows XP
- How to Enable to View Hidden Files and Folders in Windows Vista

Remove Processes from Task Manager

Press Ctrl Alt Del keys to open the Task Manager. Select Processes tab. You will see a list. Look for the names system.exe in it. Select if found and press the End Process button. It will ask for your confirmation to end that process. Select Yes. You can end one process at a time.

You can find out if a process in Task Manager is good or bad by using Windows Defender. It shows the path of a process and its publisher. Harmful processes may be shown under Unknown Publisher in windows defender.

How to use Windows Defender in windows XP

How to use Windows Defender in windows Vista

Or you can use Sysinternal's Process Explorer.

How to use Sysinternal's Process Explorer

Removing entry from windows startup

The system configuration can be started in xp and in vista by typing msconfig in the run box/ start menu search box. In xp by clicking on Start > run . The windows startup is reversible. You can check / uncheck any entry from windows startup any number of times.

Open system configuration window. Click on the Startup tab. You will see a list all the programs that are scheduled to start with windows. Expand the middle column using your mouse pointer. That will show you the full path of the program. Locate and uncheck the boxes in front of these names "system.exe" (also look for any other suspicious names) Press Apply , Press Close/Ok , Select "restart" at the next prompt.

Deleting files

The computer will restart now. Delete the following files and folders. Boot in safe mode or boot in the dos prompt if needed. You can use windows search utility to search for system.exe and find out if there are any other instances of this file present elsewhere in the computer.

Files
C:\Documents and Settings\[UserName]\Application Data\addons.dat
C:\Windows\widows\system.exe
C:\Windows\widows\logg.dat

[file and pathname of the sample #1]

(We do not know the name or the location of sample #1, it could be in your default download location or on the desktop or in a Temp folder. The files and folders in the Temp folder can be automatically removed, if you use a freeware temp files/ registry cleaner software like CCleaner)Folders
C:\Windows\widows
Registry KeysSome of the registry keys will be automatically removed if you run Registry menu of CCleaner. For others you can see the report mentioned at the beginning of this article

Using CCleaner

You can easily remove the files in the temp folder by running CCleaner. You can set CCleaner to run automatically each time the computer starts.

Do not forget to run CCleaner > Registry menu to remove the obsolete registry entries.