Prifass.sys Removal (August 2018 Update)

Parasite may reinstall itself multiple times if you don't delete its core files. We recommend downloading SpyHunter to scan for malicious programs installed with it. This may save you hours and cut down your time to about 15 minutes. 

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More information on SpyHunter, steps to uninstallEULAThreat Assessment Criteria, and Privacy Policy.

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This page aims to help you remove Prifass.sys. Our removal instructions work for every version of Windows.

Prifass.sys is a fearful Trojan threat, which has recently been reported to our “How to remove” team. Without your knowledge, this infection can perform different types of malicious tasks on your system and even potentially cause irreparable damage. That’s why, the more you know about it beforehand and understand how to protect your PC and detect it on time, the better the chances of avoiding this nasty Trojan are. If Prifass.sys has already infected you, however, on this page, we will share some useful information on how to remove it and, of course, how to prevent and protect your system in a reliable way in future. So stay with us to find out more. A detailed Removal Guide is available further in the text as well as a trusted malware removal tool, in case you need professional assistance.

Why is Prifass.sys so dangerous?

Do you know that as per some recent statistics, more than seventy percent of all the online infections usually happen through Trojan horse viruses? Yes, this is a shockingly high percentage which gives you an idea of how widespread and how common these threats really are. The reason for such a great number of infections happening through Trojans is those viruses are very stealthy and oftentimes very advanced, especially regarding newer ones such as Prifass.sys. Basically, the key to the success of this type of malware is its ability to mislead the user, oftentimes being under the disguise of some harmless piece of content or some other interesting and attractive software. By making you believe that you are clicking on a legitimate ad, a link, a update notification or an email attachment from a friend, the Trojan can silently sneak inside your system and get down to its dirty business. Similarly, a threat like Prifass.sys may use disguise to infect you. Unfortunately, you may not even have an idea of what has happened, especially if you don’t have a reliable antivirus software tool, which can detect the contamination.

Prifass.sys Removal



Some of the steps will likely require you to exit the page. Bookmark it for later reference.

Reboot in Safe Mode (use this guide if you don’t know how to do it).



We get asked this a lot, so we are putting it here: Removing parasite manually may take hours and damage your system in the process. We recommend downloading SpyHunter to see if it can detect parasite files for you.

Press CTRL + SHIFT + ESC at the same time and go to the Processes Tab. Try to determine which processes are dangerous. 


Right click on each of them and select Open File Location. Then scan the files with our free online virus scanner:

Drag and Drop Files Here to Scan
Maximum file size: 128MB.

This scanner is free and will always remain free for our website's users. You can find its full-page version at:

Scan Results

Virus Scanner Result

After you open their folder, end the processes that are infected, then delete their folders. 

Note: If you are sure something is part of the infection – delete it, even if the scanner doesn’t flag it. No anti-virus program can detect all infections. 


Hold together the Start Key and R. Type appwiz.cpl –> OK.


You are now in the Control Panel. Look for suspicious entries. Uninstall it/them. If you see a screen like this when you click Uninstall, choose NO:



Type msconfig in the search field and hit enter. A window will pop-up:


Startup —> Uncheck entries that have “Unknown” as Manufacturer or otherwise look suspicious.

  • Remember this step – if you have reason to believe a bigger threat (like ransomware) is on your PC, check everything here.

Hold the Start Key and R –  copy + paste the following and click OK:

notepad %windir%/system32/Drivers/etc/hosts

A new file will open. If you are hacked, there will be a bunch of other IPs connected to you at the bottom. Look at the image below:

hosts_opt (1)

If there are suspicious IPs below “Localhost” – write to us in the comments.


To remove parasite on your own, you may have to meddle with system files and registries. If you were to do this, you need to be extremely careful, because you may damage your system.

If you want to avoid the risk, we recommend downloading SpyHunter
a professional malware removal tool.

More information on SpyHunter, steps to uninstallEULAThreat Assessment Criteria, and Privacy Policy.

Type Regedit in the windows search field and press Enter.

Once inside, press CTRL and F together and type the virus’s Name. Right click and delete any entries you find with a similar name. If they don’t show up this way, go manually to these directories and delete/uninstall them:

  • HKEY_CURRENT_USER—-Software—–Random Directory. It could be any one of them – ask us if you can’t discern which ones are malicious.
    HKEY_CURRENT_USER—-Software—Microsoft—-Windows—CurrentVersion—Run– Random
    HKEY_CURRENT_USER—-Software—Microsoft—Internet Explorer—-Main—- Random

What possible harm may Prifass.sys cause?

Once inside the system, the Trojan can cause a number of issues, some of which could make your PC unstable or completely unusable. The most dangerous thing about threats like Prifass.sys, however, is that often nobody can really tell you what exactly they may be up to. The criminal creators, who control the Trojan, can set it to perform a specific harmful task, which could target your data, your computer resources, the software you have, certain processes in the operating system and many more. The results of the contamination could be deletion of files, disk formatting, changes in the way your programs operate, sudden system errors, crashes, or theft of sensitive information and personal espionage. Just the idea that someone with malicious intentions can have so much control over your computer is frightening enough to make you remove Prifass.sys immediately. What is more, if not removed on time, such malware can insert other viruses (such as Ransomware, Spyware, Worms, etc.), inside your system which can blackmail and harass you in many ways. That’s why, our advice is to scan your PC with a professional tool (you can use the malware removal tool on this page) as soon as you notice that something might not be quite right with your system. This way, you will have greater chance to save yourself from some really unpleasant consequences.

How could Prifass.sys infect you and how to protect yourself?

Some of the most popular ways for the criminals to spread their malware and infect the web users with threats like Prifass.sys is via spam messages and contaminated email attachments. A great number of people become victims of Trojans by opening and clicking on messages which appear to be sent by friends, popular companies or authorities, but the moment they interact with the message a harmful payload gets downloaded inside the system. Other possible sources could be fake ads, misleading links, compromised web pages, torrents or infected software installers and free download packages.

Due to the tricky camouflage methods and stealthy distribution techniques, most users can rarely detect and avoid a Trojan horse infection on their own. So, most of the times, the best way to prevent a potential malware transmitter is to rely on your antivirus software. This is also the best way to remove an infection like Prifass.sys effectively. If you don’t have such software or your existing antivirus is not able to deal with the Trojan, we suggest you use the professional Prifass.sys removal tool on this page, as it has been tested and has been proven to successfully detect and eliminate most such threats. Alternatively, you can follow the instructions in the Removal Guide below and try to deal with the Trojan on your own. Bear in mind though, that a certain risk for the system might be present in such a case if you don’t follow the steps carefully or delete data which is actually not malware-related. Nevertheless, regardless of what option you choose, be sure to eliminate the malware ASAP so that it can’t harm your machine.


Name Prifass.sys
Type Trojan
Danger Level  High (Trojans are often used as a backdoor for Ransomware)
Symptoms  Visible symptoms may be lacking or might be really difficult to detect without professional software. 
Distribution Method  Malicious email attachments, spam messages, fake links, harmful ads, torrents, infected software installers and others.
Detection Tool

If the guide doesn’t help, download the anti-virus program we recommended or try our free online virus scanner. Also, you can always ask us in the comments for help!

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