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What is Csrss.exe Virus and How to Remove it?

What is Csrss.exe Virus and How to Remove it?

It is quite disheartening, not to mention bothersome when one sees a critical Windows process become corrupt, or the undetected advance of a virus parading as an indispensable Windows system file. It is even worse when all of it leads to the foreboding Blue Screen of Death. If you are going through something similar because of the csrss.exe file, this article will guide you to handling the issue with ease.
Padmini Krishna
What is a Trojan Horse Virus?
A Trojan horse generally plays the role of providing backdoor access to a computer's system files and documents, mostly leading to a complete system crash. Since they can disguise themselves as innocuous programs, they are often willingly downloaded by users who unknowingly open malicious email attachments, or download software updates.

Interestingly, it derives its name from the legend of the wooden horse left behind by the Greeks in the epic war of Troy (Homer's The Odyssey) to which the Trojans took a fancy, and themselves dragged into their impenetrable fortress, leading to their defeat.
As you may have deduced by now, if your computer is under siege of a Trojan horse virus, it is bad news indeed. A Trojan can attack your computer so viciously that sometimes all you are left with is the menacing Blue Screen of Death, the road to recovery from which is very thorny. However, before you panic, keep in mind that the instance of csrss.exe running on your Windows-powered computer may not even be a virus in the first place.

In fact, csrss.exe (the legitimate one of course) is not just a trustworthy Windows system file, but is also a core process whose timely execution is crucial to your computer's smooth running.
A Brief Overview of the csrss.exe Windows Process
The name of this process, csrss.exe, is nothing but the short form of Client/Server Runtime Subsystem, a critical Windows component. To understand what its role is, an overview of certain applications, modes and functions of the Microsoft Windows OS is first required.

The Win32 Console is a programming interface (or environment), which is more familiarly recognized as the command line interface or MS DOS prompt. Its primary use is to program the Windows kernel. This manner of computer-user interaction can be adopted either voluntarily (when a user himself/herself opens the command prompt) or involuntarily (it may even open up by itself, for example, during the computer's booting process, its operation in safe mode, or when it runs into an error). This kind of interaction with the system is called the Kernel Mode.

On the other hand, the average user interacts with the Windows OS with the help of its Graphical User Interface (GUI) that is also known as the User Mode.

Csrss.exe is a process that keeps the Windows GUI in place. Csrss.exe manages literally everything to do with the User Mode, from the initiation and smooth running of the various software threads, to the absolute start up/shut down of the GUI at various instances. Additionally, it handles any interaction with the computer via the Win32 Console. If the csrss.exe process malfunctions, fails, becomes corrupt, or ceases to exist, the computer will not be able to launch the User Mode, and the Blue Screen of Death, a stalemate situation for the user as he (or she) cannot proceed in any direction from this point, will take over.

Users should therefore NEVER delete the csrss.exe process from the computer, and in fact they should refrain from even terminating its instance from the Windows Task Manager. If they do, indeed, suspect that they are dealing with a virus, on the off-chance that they are mistaken, they should avoid dealing with the problem themselves, and instead leave the job to the anti-virus software installed on their computer.
How to Distinguish Between the csrss.exe Windows Process and the Virus
Ask yourself the following questions.
  • Has your computer significantly slowed down?
  • Are you frequently running into errors that tell you that the running application has abruptly terminated?
These two markers are surefire indicators of trouble, generally, the presence of a virus in the computer. It is a well-known fact that creators of malware often disguise their programs to look very similar to genuine system files, so as to be overlooked by users and anti-virus software. They go as far as to adopt exactly the same name as verified system programs. Thus, quite often, they succeed in escaping detection, and creep into the computer.

Open the Windows Task Manager by simultaneously holding down the CTRL, ALT and DEL keys on your keyboard, and clicking on the appropriate option in the screen that ensues. In the Windows Task Manager, open the Processes tab. Here, search for instances of the csrss.exe process.

Once you locate them, keep an eye out for the following distinguishing markers that will help you tell apart the genuine process from a virus:

★ 1. If you have up to two instances of this process running, you are good to go. More than two, however, should set off the warning bell in your mind, unless you are fast-switching your user modes, or accessing your computer from a different system, remotely.

★ 2. Look at each instance of csrss.exe itself. If you do not have administrative privileges, the adjacent column, entitled User Name, will be blank for this process. Without gaining administrative access, users cannot even view the properties of this particular process.

★ 3. After logging in as the administrator, users can see that the username associated with this process is "SYSTEM".

★ 4. This file has an average size in between 5 KB and 8 KB, and as a running process, it takes up around 3000-5000 K of CPU memory.

★ 5. The genuine file is located at the following path:
Any file with a similar name located in any other folder, including the parent Windows folder, is not bona fide, and may in fact be a virus in disguise.

★ 6. You cannot shut down this process without logging into the computer as the administrator, and even if you try after gaining access to admin privileges, Microsoft presents you a warning asking you to rethink your decision of shutting it down, stating that you will end up shutting down your OS entirely. If nothing hinders your attempt to terminate the csrss.exe process, it may be a virus, and not the genuine process.

If you feel that the various issues in your computer have some connection to csrss.exe, but you are unable to find any evidence to suggest that it may be a Trojan horse or any other kind of virus, remember that it could even be possible that the verified csrss.exe file may itself be infected by a worm, causing trouble for your computer.
Getting Rid of the Csrss.exe Virus
So now that you have plausible doubt that you are harboring a malicious csrss.exe file in your computer, it is time to take steps to get rid of it.

★ 1. Start by running a full system scan for viruses on your computer with a powerful anti-virus software such as Norton, McAfee and the like. If csrss.exe shows up on the radar, use the anti-virus software's built-in tools to rid your computer of it. If the software gives you no indication of a virus infection, chances are that your computer is giving you trouble because of an entirely different reason.

★ 2. Suppose your anti-virus software detects the csrss.exe virus, but is unable to delete it, do not panic; it can be done manually too.

★ 3. Csrss.exe is a hidden file, so if you want it to appear in any search results, the option that allows you to view hidden files needs to first be enabled. The method to do this varies for different versions of Windows.

On Windows XP and preceding versions,

  • Open My Computer.
  • In the menu bar, click on Tools, and in the drop-down menu that appears, click on Folders.
  • In the window that opens, open the tab labeled View.
  • Look under Advanced Settings for the option regarding hidden files and folders.
  • Select the option labeled Show hidden files and folders, following which, uncheck the option labeled Hide extensions for known file types.

On Windows Vista and subsequent versions,

  • Open My Computer.
  • Click on Organize, the first button on the top-left corner, and in the menu that drops, click on Folder and Search Options.
  • In the window that opens, open the tab labeled View.
  • Look for the option regarding hidden files and folders.
  • Select the option labeled Show hidden files and folders, following which, uncheck the option labeled Hide extensions for known file types.
★ 4. Once you have ensured that files having this name and extension will show up in the search results, it is time to locate it. Open the Start menu, and in the search box, type "csrss.exe". Bear in mind that in order to escape detection malware sometimes even carry miss-spelled names of known files, and so keep an eye on whether you can detect any process with a very similar, yet not exactly the same name as csrss.exe.

★ 5. Rule out any instance of csrss.exe that is located at the aforementioned path, as that is actually the genuine file, and must not be deleted under any circumstances. Right-click on their name of each of the other instances and select Open File Location.

★ 6. Once you open the folder in which the suspicious file is located, delete it. Be very careful to ensure that you are not erroneously trying to delete the legitimate csrss.exe file.

★ 7. If you are unable to delete it, right-click on it, and select Cut from the drop-down menu. Paste it on your desktop, rename the file in such a way that it now has any arbitrary name followed by a .txt extension. Now delete the file.

★ 8. If in spite of following all these steps you are still unable to delete it, make note of the original path of the troublesome file. Open the Start Menu and type "cmd" in the search box to launch the command line interface. Here, type "del" followed by the path of the malicious csrss.exe file. You will definitely be able to delete it.
Sometimes, you may suspect that your csrss.exe file is a virus because it has engaged an abnormally large portion of CPU memory. This does not necessarily mean that the process itself is corrupt, but rather, probably your Windows user profile may be running into an error. This problem can be easily rectified by deleting and creating a new user profile.
We hope we could help you solve all your problems stemming from the csrss.exe process. Make sure you pinpoint the origin of your problem before deleting any system files. Never hesitate to invest in a strong anti-virus software, which will not just detect and clean up any malware, but also defend your system right from the first instance of any virus attack.