What is Rundll32.exe Process? Is it a Trojan or Virus?

Rundll32 process. Explaining the purpose.
rundll32, rundll32.exe
Written by Wilbur Woodham

Rundll32.exe process is an internal Windows process, which carries an important function. However, different malicious programs mimic this process to stay longer in the system. In this post, you will see the explanation of the task of the rundll32.exe process. Besides, I will show you the ways of recognizing that this process is a counterfeit.

Why this process is needed?

This system application is essential for the correct system functioning. The main task it carries is a correct execution of the programs, based on dynamic-link libraries (DLL). DLLs act as toolkits that allow the creation of the functions in the program. Every program needs its chain of dynamic-link libraries, and to make the calling of these DLLs easier, Windows offers such a function.

Besides these functions, rundll32 also allows calling different system functions manually, from the command prompt. For example, to call the Control Panel, you need to type the next command:

RUNDLL32 SHELL32.DLL,Control_RunDLL filename.CPL,@n,t

Rundll32 functions usage

Where “filename” is the exact name of the Control Panel file, “n” is an applet of the CPL file, and “t” is the number of tabs the applet has (if it has several ones).

Such functions open a wide range of abilities for software developers, who don’t need to create a separate way of system function calling. Instead, they may make use of the embedded Windows mechanism.

Can I stop rundll32 exe?

You will not likely find this process in the classic Task Manager. It is hidden from the user without any clear reason. The only way to spectate the rundll32 process is to use another task management application from Microsoft – Process Explorer. It allows you to see a lot of different hidden processes, including the subject. Stopping this process will surely lead to various problems with the applications that require this service to be active. Moreover, that process consumes tiny amounts of CPU/RAM capacity, so there is no need to suspend it.

The times when Windows processes may be disabled to increase the system performance have passed long ago. When Windows XP was the last actual OS version, computers were quite weak, and their upgrade was expensive. Disabling several services could make your PC faster without any significant problems. Nowadays, such tricks can make things even worse.

How can I understand that rundll32 is a virus?

This week, when I was away and had my laptop with me (without an internet connection), I noticed that my rundll32.exe was infected. I first saw it when I attempted to run games or other programs. On my first attempt, most would not run, and I would check the task manager to find rundll32.exe taking around 35~40% of my CPU, and the game process is listed, but the game is not running. Running the same game or program a second time would make it work, though rundll32 would keep running in the background at high CPU usage and remain even after I closed whatever program I was using until I manually ended its process.

The perfect way to check if a malicious program launches the process is to open its file location. Find the rundll32.exe process in Process Explorer, and click it with the right mouse button. Choose the “Open file location” option, and you will see the folder where the .exe file is located. Everything is okay if the source file – rundll32.exe is located in C:/Windows/System32. Any other source file location means that you have malware on your computer. A wide range of viruses mimics this process, copying its name. To check your PC for viruses, I can offer you to use GridinSoft Anti-Malware1.

Rundll32 exe file location

Proper location of rundll32.exe file

Removing the viruses with GridinSoft Anti-Malware

  • Download and install the GridinSoft Anti-Malware. After the installation, you will be offered to perform the standard scan. Apply this action.
  • GridinSoft Anti-Malware during the scan process

  • Standard scan lasts up to six minutes and checks the system files together with the files of the programs you have installed on your computer.
  • GridinSoft Anti-Malware scan results

  • When the scan is complete, press “Apply” to wipe out the malicious items that are present on your PC.
  • Malware removing with GridinSoft Anti-Malware

    Frequently Asked Questions

    Can I delete the process from the root directory?

    No. If the process belongs to the legitimate system element, you will not be able to edit the system’s root directory, where it is stored, without permission for this action. And its deletion will undoubtedly lead to a system crash without the possibility of loading the system back because the crucial component is absent.

    Is it possible to decrease the hardware consumption of this process?

    That process consumes nothing, so you will likely see no occasions when there is a need to make it less greedy with resources. However, it is expected to be a virus if you know that it takes more than 20-30% of your CPU and the same amount of RAM. Perform the guide I wrote above.

    How can I know this process is malicious without checking its root directory?

    As was mentioned in the previous question, the CPU/RAM consumption of the actual process is deficient. So, the rundll32 process that uses a lot of hardware capacity is a virus. Another way to understand that this process belongs to a malicious program is its location inside the Process Explorer. System processes are listed in the corresponding thread so that process application among the user’s background processes is a sign of malware presence.

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    1. Explanation why do I recommend you to use GridinSoft Anti-Malware.
    Rundll32 process. Explaining the purpose
    Rundll32 process. Explaining the purpose
    Rundll32 is a system process which is responsible for correct DLL usage for every app. It is often counterfeited by malicious programs.

    About the author

    Wilbur Woodham

    I was a technical writer from early in my career, and consider IT Security one of my foundational skills. I’m sharing my experience here, and I hope you find it useful.

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