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.

Click to Run a Free Scan for dllhost.exe related errors

Dllhost.exe file information

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

The process known as COM Surrogate or C?m Surr?gate or Microsoft Fax Cover Page Editor belongs to software Microsoft Windows Operating System or COM+ System Applications or cito by Microsoft ( or apatia chi.

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 10/8/7/XP are 7,168 bytes (48% of all occurrences), 5,120 bytes and 22 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 4% 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.GZP (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

I know that without it you would not be able to fix or track what is going on with your computer, I would rate it as a high importance
  Maryanne Quenneville   (further information)
just what Ive read. Its creeps the memory up and up until my computer stops working and basically crashes
How to move file requesting permission When you have located the file... right click on the file and select properties; Security tab; Advance; Owner; Edit. Change owner to Administrators. Next go to Effective Permissions tab; Select; Advance; Find now. Choose Administrators. Next go to Permissions tab; Change Permissions; Edit. Under permission entries there is a list of names. Give administrator full control. Give System Full control. Give Users full control. "Clear all" permissions from other names listed. Next: Apply; ok. Then click the "X" in the right hand corner of the Properties menu. When you check the properties for the file again you should see under security tab "Group or user names:" Permissions for SYSTEM: full control; Permissions for Administrators: Full control; Permissions for Users: Full control. Once that is done the file should be able to be removed to another location or deleted once it is not running in task manager.
Dllhost.exe crashed often by a broked audio or video codec. Google for "Microsoft Fix it Codec Run" to fix it, or see the link.
  Ax   (further information)
My internet is very slow but when i open my task manager i delete process tree it speeds internet. the dllhost is opening every 10 seconds.
  Luka Saponjic  
My CPU is 100% because of dllhost.exe. Not sure why, but if I disconnect from the internet by turning the power off on my router, then restart my Windows 7 PC the problem goes away.
  Bob F  
After hours of trying to figure out how to stop it from using all the memory, I went and deleted the file dllhost.exe and the problem finally went away. In your Windows Task Manager right click on dllhost.exe *32 COM Surrogate and click on Open File Location. It will open the folder C:\Windows\SysWOW64 and with the file dllhost.exe selected. To delete it you need to have ownership. To do that right click dllhost.exe and then go to properties. Select the Security Tab and Select the Administrator and click the Edit and select Administrator from the list and from the buttom for Full control click the check box and apply and OK and OK. Now try to delete the file. If you get a message that "The action can't be completed because the file is open in dllhost.exe", Open Task Manager and click on the check box for Show processes from all users at the bottom to show the dllhost.exe for all users. Now right click on each of the dllhost.exe *32 COM Surrogate and End the processes. Once you have ended every one of them, then go back to C:\Windows\SysWOW64 folder and delete the dllhost.exe file. Thats it. Hope it helps.
More comments can be found here:
    (further information)

Rating chart

Summary: Average user rating of dllhost.exe: based on 270 votes with 9 reviews. 108 users think dllhost.exe is essential for Windows or an installed application. 13 users think it's probably harmless. 49 users think it's neither essential nor dangerous. 36 users suspect danger. 64 users think dllhost.exe is dangerous and recommend removing it. 34 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 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic 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 6resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the 7DISM.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: ASecurity 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. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

dllhost.exe [all]