How to remove Microsoft\Svhost.exe

Microsoft\Svhost.exe

Monday, 04 October 2010 01:40

The file name C:\Documents and Settings\[UserName]\Application Data\Microsoft\Svhost.exe along with other file names has appeared in a virus analysis report. You can see it on this link

It seems that it has not been detected by Antivirus programs. That makes it more harmful as it can stay undetected on your computer. However its characteristics indicate that it could be Trojan Bifrost.

The initial installer is about 187 KB.
It installs a component of backdoor Trojan Bifrose or BiFrost.
It allows hackers to control infected computers even if they are behind firewalls and routers.
It can download harmful files from the internet.
It infects Internet explorer browser. It attaches a keylogger with Internet Explorer. That will steal your user ID and passwords. It is detected that the virus hides the process "IEXPLORE.exe" so that a user is unaware that Internet Explorer is running in the background.
It creates a new memory page in the address space of the system process
C:\Windows\pchealth\helpctr\binaries\helpsvc.exe

(You should End this process through Task manager before removing the virus files, However this is a system process, you should not delete the file)

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

warning icon Statutory Warning: It is possible that some legitimate software may be using the same file names as that of the virus files. You do not have to delete these files, if they belong to some legitimate program installed on your computer. Use Windows Defender or SysInternals Process Explorer to differentiate between them. This article is based on available information on the internet. In case of dispute, please send me a note by adding a comment at the end of this page, or mail me on support(at)comprolive.com

You can also use one of the Free online Virus scanning and removal services listed on this link

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
Using system restore in windows7

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
How to boot in safe mode in windows7

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
How to Enable to View Hidden Files and Folders in Windows7

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 Svhost.exe, clr.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 in XP and Vista. It shows the path of a process and its publisher. Harmful processes may be shown under Unknown Publisher in windows defender. Whereas in Windows7 you can find that out from the task manager itself

How to use Windows Defender in windows XP
How to use Windows Defender in windows Vista
How to use Windows Defender in windows7

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 "Svhost.exe, clr.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 Svhost.exe, clr.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\Microsoft\Svhost.exe
C:\Windows\pchealth\helpctr\Config\Cache\Professional_32_1033.dat
C:\Windows\pchealth\helpctr\Config\CheckPoint\tmp.edb
%Temp%\Svhost.exe
%Temp%\clr.exe
%Temp%\MPC2.tmp
%Temp%\Read Before Install.nfo
[file and pathname of the sample #1]

Folders
none

(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)

Registry Keys

Some of the registry keys will be automatically removed if you run Registry menu of CCleaner. For other registry changes 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.