How Do Virus Scanners Work?

How Do Virus Scanners Work?


Keeping yourself safe with a VPN like Surfshark or PureVPN is only part of ensuring that nothing befalls you on the internet. Bet you never thought you’d hear us at PinpointVPN say that! Keeping yourself safe from viruses is an essential part of ensuring that your computer remains fully functional and that your data remains safe.

However, have you ever considered how virus scanners work and what they actually do to catch the pesky viruses that slip through the cracks? If you have, you’re in the right place. In this article, we’re going to take a look at what a virus scanner is, what it does, and how to pick the right one for your needs.

What is a Virus Scanner?

A virus scanner is a synonym for antivirus software, and these programs exist to ensure that your devices are kept free of malware. While most traditional antivirus programs are used on computers, more and more antivirus companies are producing mobile programs with the rise of mobile malware.

A virus scanner detects the viruses that are present on your computer and then uses its included tools to remove those viruses. While no virus scanner is 100% effective, most of them are effective enough for personal use, since you’re unlikely to run into an undetectable supervirus if no one has a reason to target you.

Reasons to Use a Virus Scanner


So why should you use a virus scanner in the first place? The most obvious reason is to ensure that your device (PC, phone, tablet, etc.) is kept as safe as possible. Since virus scanners stop viruses in their tracks, you can ensure that your computer doesn’t get bricked or that your data doesn’t get leaked.

There are countless different types of viruses on the internet, ranging from adware, which is often relatively harmless to ransomware which will lock up all of your computer’s files unless you send a payment to the hack’s creator. Unfortunately, removing viruses can be hard work.

Due to the way that viruses work, you can never be sure that your computer’s factory-clean ever again once you get a virus. This is because most viruses can’t be fully detected by virus scanners. Rather, virus scanners remove the responsible files, but those files may have left malicious code behind on your machine.

To ensure that you don’t end up on the wrong end of a virus, you’ll want to invest in a quality virus scanner. This will allow you to check files before running them to ensure that they don’t contain any malicious software that’s going to run on your machine as soon as you open them up.

How Do Virus Scanners Work?

A virus scanner operates by using a blacklist, and this helps ensure that your computer remains protected from threats whenever possible. This blacklist contains every kind of virus that has already been detected by the antivirus company that is responsible for developing your virus scanner.

When a file that is on the blacklist has been detected by your virus scanner, it will delete the file and ensure that it’s not able to run. If it is unable to delete the file, it will quarantine it to ensure that it can’t do any damage to your system while it works out a way to get rid of the file.

There are a few different kinds of scans that a virus scanner can conduct. The most common type is a real-time scan that will go over your system in the background. These scans check in the most common places that viruses are known to hide, and they also scan files and programs before you open them.

If you’re looking for a more comprehensive way to ensure that your computer is free of any viruses, then you’ll want to conduct a system scan. System scans take a bit longer than real-time scans and they go through each and every file directory in your system looking for hidden viruses.

System scans can be conducted manually but you can also schedule them so that they’re conducted regularly to keep your computer safe. Most users conduct at least one of these scans per month to make sure that there’s no hidden malware stealing all of their information.

What is a Virus Scanner Blacklist?

Virus scanner blacklists are relatively simple. They are essentially a database of viruses that have already been detected and they are used to cross-reference the viruses that the program finds on your computer. If a file matches something on the blacklist, then it will be detected as a virus.

The files on a blacklist are known as definition files, and they are constantly being compared and matched to files that the virus scanner is going through. The quality of a virus scanner is often directly dependent on the quality of its blacklist, since that will determine whether or not it can catch viruses.

How Does Predictive Detection Work?

Predictive detection is a little more in-depth than a blacklist, and it essentially works through heuristics. If you’ve ever seen your virus scanner say that it’s conducting a “heuristic analysis” of the files that it went over, that means that it’s using its powers of predictive detection to find potential threats.

Predictive detection is used to find viruses that aren’t in a virus scanner’s database but have certain features that are similar to existing viruses. This has the advantage of adding new viruses to the blacklist but it also ensures that your machine won’t get swamped with other forms of malware.

Along with using features of already detected malware to find new ones, predictive detection also determines when a particular program is acting out of line. For example, if a program suddenly starts trying to overwrite your computer’s code, then there’s probably something wrong with it.

One of the main issues with this form of virus detection is that it can sometimes be wrong. This means that it may result in false positives that will require you to manually override the antivirus so that you can use certain programs, especially if they’re homebrewed programs without security certificates.

Is a Free Virus Scanner Worth It?

Free Virus Scanner

If you can’t afford a premium virus scanner, you may consider using a free scanner. There are a few downsides to free scanners that you should know about before using one of them. For example, many of them won’t offer free real-time protection, so you may be left vulnerable when opening new files.

Another downside to free antivirus programs is that they often have outdated blacklists that may not contain all forms of malware that are potentially infecting your computer. This makes it harder for you to be sure that your computer is 100% safe, though it’s probably better than using nothing at all to protect your computer.

While some might argue that free virus scanners also contain malware of their own, this is extremely rare and only possible if you download your virus scanner from a disreputable company. For example, Malwarebytes is an excellent free virus scanner that contains no traces of malware.

It’s always a good idea to keep your computer protected. As long as you’re aware of the shortcomings present in your choice of free virus scanner software, then you’ll be able to make up for them. However, if you just want the virus scanner to handle everything for you itself, you’re better off with a paid option.

Features to Look for in a Virus Scanner

There are a few key features that you should account for when searching for the best possible virus scanner. If you’ve never shopped for antivirus software before, then you’ll want to go over these features so that you can be sure that you’re getting the best possible piece of software for your money.

Ease of Use

One of the most important things to make sure of is that your virus scanner is easy enough for you to use. You don’t want to end up with a virus scanner that’s too challenging for you to even operate properly, especially if you’re not used to working with more complicated software.

Be sure to take a look at how the UI of your virus scanner is designed and how it presents the available options to you. Nobody wants to have to root around in countless menus just to find a crucial feature that will stand between their computer being healthy and it getting infected.


Some virus scanners also come included with additional features that may tip the balance in their favor. For example, your virus scanner may include a VPN or a secure browser that will allow you to more easily browse the internet without having to worry about your privacy being invaded.


Always check to make sure that your antivirus program is compatible with your computer. Some virus scanners will work on both Macs and PCs while others will only work on one or the other. It would be an unpleasant surprise to see too late that your virus scanner doesn’t work with your computer.