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.

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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 Een DLL-bestand als toepassing starten or Exécuter une DLL en tant qu'application or Ejecutar un archivo DLL como una aplicación or Uob or Windows værtsproces (Rundll32)

belongs to software Microsoft Windows Operating System or Betriebssystem Microsoft Windows or Besturingssysteem Microsoft Windows or Sistema operativo Microsoft Windows or Système d'exploitation Microsoft Windows or Microsoft Windows Operativsystem or Lsz or Microsoft DRM

by Microsoft ( or Ocf or judokas négligent or Simple Productions or skb or DODQKDZQR or Microsoft Windows Operating System ( or url.

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 8/7/XP are 33,280 bytes (60% of all occurrences), 33,792 bytes and 49 more variants. 
The file is a Microsoft signed file. Therefore the technical security rating is 6% 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 TROJ_VB.CHK or PE_VIRUT.AV (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

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
run dll32.exe can be both harmful and neutral, what it is, is a execution program run by windows so that it can startup all the windows nonsense like explorer.exe, but some clever person from poland in 1980s found a way they could use this to run a selected program that they have planted on your computer, ie a virus downloaded from the internet because normally they would have to make there own executional file to start the virus process, but using the rundll32.exe was much better because it could use it as a way to mask itself and tricked antivirus software into thinking that it was windows opening the dll until Dr. Solomon created his Anti-Virus Tool-kit to remove them. if it appears in upper case letters then it will probably be some home made virus and i would consider removing it, ps, ANDREW - the *32 is normal it just means that you have a 32 bit computer, (how many bits of data your computer uses) but you don't need to know the technical stuff.
Don't touch or edit the file lets pretend it it is the you kill it you kill kernel32.dll = computer dies :( see your self
  Vincent Bartolo  
More comments can be found here:
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Rating chart

Summary: Average user rating of rundll32.exe: based on 476 votes with 9 reviews. 167 users think rundll32.exe is essential for Windows or an installed application. 21 users think it's probably harmless. 120 users think it's neither essential nor dangerous. 70 users suspect danger. 98 users think rundll32.exe is dangerous and recommend removing it. 76 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 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 rundll32.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

rundll32.exe [all]