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.
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 (www.microsoft.com) or Ocf or judokas négligent or Simple Productions or NEXT-Soft or Microsoft Windows Operating System (windows.microsoft.com) 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 (56% of all occurrences), 33,792 bytes and 40 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
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?
If rundll32.exe is located in a subfolder of C:\Windows, the security rating is 10% dangerous. The file size is 44,544 bytes (75% of all occurrences), 51,200 bytes and 12 more variants. The program is not visible. Rundll32.exe is a trustworthy file from Microsoft.
If rundll32.exe is located in a subfolder of the user's profile folder, the security rating is 58% dangerous. The file size is 24,576 bytes (18% of all occurrences), 120,992 bytes and 17 more variants. The file is not a Windows core file. There is no description of the program. The application starts upon Windows startup (see Registry key: MACHINE\Run, Run, MACHINE\RunOnce, DEFAULT\Runonce, User Shell Folders, DEFAULT\Run, Winlogon\Shell, win.ini, Userinit, MACHINE\RunServices, MACHINE\User Shell Folders). The program has no visible window. Rundll32.exe is able to record keyboard and mouse inputs, monitor applications and manipulate other programs.
If rundll32.exe is located in a subfolder of "C:\Program Files", the security rating is 37% dangerous. The file size is 33,280 bytes (25% of all occurrences), 33,792 bytes and 4 more variants.
If rundll32.exe is located in the C:\Windows folder, the security rating is 77% dangerous. The file size is 44,695 bytes (25% of all occurrences), 52,376 bytes and 5 more variants.
If rundll32.exe is located in a subfolder of C:\, the security rating is 67% dangerous. The file size is 61,440 bytes (75% of all occurrences) or 44,544 bytes.
If rundll32.exe is located in a subfolder of Windows folder for temporary files, the security rating is 56% dangerous. The file size is 310,359 bytes.
If rundll32.exe is located in a subfolder of C:\Windows\System32, the security rating is 52% dangerous. The file size is 376,851 bytes (50% of all occurrences) or 256,512 bytes.
If rundll32.exe is located in the Windows folder for temporary files, the security rating is 54% dangerous. The file size is 20,480 bytes.
If rundll32.exe is located in a subfolder of the user's "Documents" folder, the security rating is 56% dangerous. The file size is 7,168 bytes.
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.
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 repairing of your installation or, for Windows 8 and later versions, 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.