What is dllhost.exe?

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the dllhost.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

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Dllhost.exe file information

Windows Task Manager with dllhost
Dllhost.exe process in Windows Task Manager

The process known as COM Surrogate belongs to software Microsoft Windows Operating System or COM+ System Applications or Panasonic Document Management or WINS Client or cito or Windows Host Services or TestAOL7Extract by Microsoft ( or Noco or apatia chi or Tybee Software.

Description: The original dllhost.exe from Microsoft is an important part of Windows, but often causes problems. The file dllhost.exe is located in the C:\Windows\System32 folder. Known file sizes on Windows 8/7/XP are 5,120 bytes (73% of all occurrences), 7,168 bytes and 13 more variants. 
The dllhost.exe file is a Windows system file. The program has no visible window. It is a Microsoft signed file. Therefore the technical security rating is 3% dangerous; however you should also read the user reviews.

Recommended: Identify dllhost.exe related errors

Viruses with the same file name

Is dllhost.exe a virus? No, it is not. The true dllhost.exe file is a safe Microsoft Windows system process, called "COM Surrogate". However, writers of malware programs, such as viruses, worms, and Trojans deliberately give their processes the same file name to escape detection. Viruses with the same file name are such as WORM_INJECT.OB or WORM_VB.IAX (detected by TrendMicro), and W32.SillyFDC or W32.Fontra (detected by Symantec).
To ensure that no rogue dllhost.exe is running on your PC, click here to run a Free Malware Scan.

How to recognize suspicious variants?

External information from Paul Collins:

Important: Some malware disguises itself as dllhost.exe, particularly when not located in the C:\Windows\System32 folder. Therefore, you should check the dllhost.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

there is a virus that act as dllhost.exe, the genuine file should be in the System32 folder. Start Task Manger and open the proerties of the file if the location is not other than C:\Windows\System32 it is virus. To get rid of it, remember the virus file location from the properties start windows on SafeMode and locate and delete the file. Possilbe location of the virus file could be 'C:\Users\ ur name \AppData\Roaming\Microsoft\Windows\Temp'. After deleting the file restart the system normal and the virus should be gone.
Why does dllhost.exe Com surrogate consumes memory untill crash. It happens when I highlight or view a folder containing video files, Even if I close the folder or select a different folder the memory keeps getting consumed. It seems to happen mostly with 3D Video files but it has done the same with 2D files. So it seems to be a problem with the windows thumb nail system dealing with these files. By the way trying to delete or move the file or folder while the Com Surrogate is consuming memory Delete can not complete the task. What I have been doing is finding offending file selecting Delete, then go to task manager stopping Com Surrogate, then the file will delete. Fix "MS are aware of problems with certain chipset/driver combinations and the KB2670838 update They are also aware of problems with the IE10 install They are working on both issues, and will update as and when they are satisfied that they have solved the problems. The recommendation in the meantime is that if the update doesn't install first time, make sure it's uninstalled, and then hide it - Windows Update will unhide it when it is updated." So Uninstall IE10 and KB2670838 update, hide them from auto updating when thy pop back up to be updated the problem should be fixed. Proof that MS knows that IE10 has problems on some hardware platforms is here.
  Korbin   (further information)
take all of my RAM eats up system resources
  Joe P  
I don't know why people are talking about CPU and CPU. Actually In my computer, It is using a lot of memory(RAM). It hangs explorer. I didnot find it dangerous. But this is totally unusable. It doesn't matter if you terminate it and your comuter can run without running this process. And Yes of course, I want to remove this process.
  Suresh chaudhari  
I have a bunch of these files running at the same time on my computer at the same time, it is also eating lots of CPU power and memory.
Even i stopped Com+ services its running with domain id@win2008R2 server, Its loads 100% cpu
It keeps showing up and then staying for a few seconds and it then disappears from my Windows Task Manager in the processes section. It seems strange I have nothing that uses it.
DLLHOST.EXE WAS EATING 25% MY CPU. The Process Explorer showed that this was MFC thread processing thumbnails. I realized that video file on my desktop is in wrong codecs/defective and windows is trying to make thumbnail for it. Every time I showed desktop, this thread started and eat CPU. Deleting the file, fixed it. Check your desktop! Is there any video/image file that is corrupted? WIN 7 cannot handle its thumbnail creation and uses a lot of CPU.
More comments can be found here:
    (further information)

Rating chart

Summary: Average user rating of dllhost.exe: based on 248 votes with 9 reviews. 99 users think dllhost.exe is essential for Windows or an installed application. 12 users think it's probably harmless. 47 users think it's neither essential nor dangerous. 30 users suspect danger. 60 users think dllhost.exe is dangerous and recommend removing it. 29 users don't grade dllhost.exe ("not sure about it").

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Best practices for resolving dllhost issues

A clean and tidy computer is the key requirement for avoiding problems with dllhost. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off doing a repair of your installation, or in the case of Windows 8, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the dllhost.exe process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

dllhost.exe [all]