What is rundll32.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 rundll32.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 rundll32.exe related errors

Rundll32.exe file information

Windows Task Manager with rundll32
Rundll32.exe process in Windows Task Manager

The process known as Run a DLL as an App or Windows host process (Rundll32) or Eine DLL-Datei als Anwendung ausführen or Exécuter une DLL en tant qu'application or Ejecutar un archivo DLL como una aplicación or Uob or Windows værtsproces (Rundll32) or endigué chaine' définirons

belongs to software Microsoft Windows Operating System or Betriebssystem Microsoft Windows or Sistema operativo Microsoft Windows or Système d'exploitation Microsoft Windows or Lsz or Sistema operacional Microsoft Windows or ecuma gourdirions or Microsoft Windows Operativsystem

by Microsoft ( or Ocf or judokas négligent or Simple Productions or NEXT-Soft or Microsoft Windows Operating System ( or DODQKDZQR.

Description: The original rundll32.exe from Microsoft is an important part of Windows, but often causes problems. Rundll32.exe is located in the C:\Windows\System32 folder. Known file sizes on Windows 10/8/7/XP are 33,280 bytes (54% of all occurrences), 33,792 bytes and 41 more variants. 
The file is a Microsoft signed file. Therefore the technical security rating is 10% dangerous, however you should also read the user reviews.

Recommended: Identify rundll32.exe related errors

Viruses with the same file name

Is rundll32.exe a virus? No, it is not. The true rundll32.exe file is a safe Microsoft Windows system process, called "Run a DLL as an App". 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 for instance WORM_OTORUN.MS or TROJ_VB.CHK (detected by TrendMicro), and Mal/KeyGen-M (detected by Sophos).
To ensure that no rogue rundll32.exe is running on your PC, click here to run a Free Malware Scan.

How to recognize suspicious variants?

External information from Paul Collins:
There are different files with the same name:

Important: Some malware disguises itself as rundll32.exe, particularly when not located in the C:\Windows\System32 folder. Therefore, you should check the rundll32.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 have never see this in task manager until today I see it, I found out that this program is located in system32 folder
There is a good file by microsoft called "rundll32.exe" located in System 32, but on 4/23/14, a virus under the same name that makes your system crazy slow or crash. It is a real virus. I believe it comes from a trojan called "slrundll."
The windows required rundll32.exe... But the hackers attack this file crash the pc And the most of the virus and malware s written by hackers for attack this file... If you want to prevent this .. Make your pc is well secured antivirus..
  Rask in  
The file itself is not a virus, but there is a virus under the same name.
This is a valid Windows program used to run DLLs (hence the name). YES there are also viruses out there that use the same name, and YES viruses can exploit and screw with your rundll32.exe file, just as they can screw with any of your files, and YES sometimes you will have system or registry errors that cause it to not run properly... but the file itself is safe, valid, and necessary for certain functions. If you're having rundll32.exe problems, rundll is not the cause, unless you have a second illegitimate rundll32 file hiding on your system somewhere.
Just leave it it will dont do any thing ..... Dont rename it or dont do any more .....
  diwan chowthry  
Multiple instances of RUNDLL32 may be running on your pc at one time. Some of these may or may not be the legitimate versions.
Hit start type MRT (Malware Removal Tool). This is included in every Mircosoft Computer choose full scan and follow the steps. It is a good idea to do this in safe mode
More comments can be found here:
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Rating chart

Summary: Average user rating of rundll32.exe: based on 485 votes with 9 reviews. 171 users think rundll32.exe is essential for Windows or an installed application. 21 users think it's probably harmless. 121 users think it's neither essential nor dangerous. 70 users suspect danger. 102 users think rundll32.exe is dangerous and recommend removing it. 77 users don't grade rundll32.exe ("not sure about it").

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Best practices for resolving rundll32 issues

A clean and tidy computer is the key requirement for avoiding problems with rundll32. 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 rundll32.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

rundll32.exe [all]