How does an Anti-virus Work for Protecting Computer


Antivirus software is one of the most important and must-have Windows. Why is this program important? This is because your computer needs extra protection from some sort of malwares or viruses. Have you ever wondered how an antivirus detects a virus? What can an antivirus do for your computer? Is it necessary to scan your computer every time? In the following explanation, we will give you the answer.

Techniques to detect Anti-Viruses

An antivirus offers several techniques to detect viruses on your computer, such as:


Previously, antivirus software relies heavily on signatures to detect malware on a computer. Basically, when malware is found by antivirus company, it will be analyzed by researchers or dynamic malware analysis systems. Then after a malware is confirmed, the proper signature of the malware extract file will be added to the antivirus signature database. When files are scanned, antivirus software will compare the contents of files with malware signatures in the signature database. If there is a file that matches with one of the signatures, then the antivirus will determine the types of malwares and the procedures to do to avoid infection.


Antivirus software also contains a heuristic. So what is a heuristic? Heuristic allows antivirus software to identify new types of malware, even in the absence of virus definition file. For example, if an antivirus detects an application is running on the system and trying to open any EXE file on your computer, infecting it by writing a copy of the original application, the antivirus will detect this application as a new file, known as unknown viruses.

There is no such perfect antivirus software. Heuristics can not be too aggressive or they will be marked as a virus.


Do you know that an antivirus can do a rootkit scan? A rootkit is a type of malwares that is created to enable controlling the administrative system of the computer without being detected. This is one of the most dangerous viruses, because it can control your computer. Rootkit can modify all system functions on the operating system, so it could make the antivirus powerless to detect it. Rootkit is also a tough malware to be removed; most of them must be resolved by reinstalling the operating system.

Real-time protection

Real-time protection or the protection of real-time, on-access scanning, background scanning, resident scanning and other terms is aimed for automatic protection belongs to the majority of antiviruses. This technique will monitor the computer system at any time to see any suspicious activity of viruses, spyware, adware or malware.

Scanning Process

Antivirus software runs in the background, checking all the files on the computer. This process is known as on-access scanning, background scanning, resident scanning, real-time protection, and the like, depending on the antivirus you use.

When you double-click on the EXE file, you will see the file opens, but it really is not. First, the antivirus will check your application, comparing it with viruses, worms and other types of malware. Antivirus also heuristically examines the application with a new type or an unknown virus.

Not only with the EXE file, has it also scanned all files with other formats. For example, a zip file containing a compressed virus or Word documents that may contain malicious macros. The file will be scanned each time it is used or opened.

Full System Scan

With the existence of on-access scan, it is no longer necessary to do a full system scan. If you download a virus on your computer, the antivirus will immediately inform you so you do not need to manually scan it.

However, the full system scan can still be useful for some conditions. A full system scan is helpful when you just install antivirus software; it makes sure that no virus lodged in your computer. Most antivirus software has a schedule of full system scan, usually once a week. This ensures that no new virus can infect your computer.

Virus Definition

Your antivirus software relies on virus definition in detecting malware. That’s why the antiviruses always update themselves automatically, including updating the database definition. The definition file contains information about new viruses or malware that exists in the world of technology. When antivirus scan files and tell you that there is a suitable file with the malware, the antivirus software will stop working and put it into quarantine. Depending on the antiviruses settings you have, the anti-viruses may automatically delete files or run the file if you are sure that the file is not a virus.

The antivirus companies have an obligation to perform continuous updates on the latest malware database, releasing an updated definition that ensures malware trapped by their software. The antivirus lab uses a variety of tools to uncover viruses, to run them in a sandbox, and releasing timely updates so that users are protected from any malware.

False Positive

Since the number of existing software in the world is abundance, it is possible for an antivirus to false detect the file as a virus even when it’s a very safe file. This situation is usually called a False Positive. Sometimes the antivirus companies also make the mistake of identifying the Windows system files, the popular third-party software, or antivirus file as a virus.

Heuristics can also increase the rate of false Positive. The antivirus may see it as an application that is similar to malicious applications and identify it as a virus.

However, false positives are rare when normal use. If the antivirus tells you of a malicious file, do not immediately believe. If you’re not sure whether that file is actually a virus, you can try to upload it to VirusTotal (virus checker site owned by Google). The VirusTotal will scan files with a wide range of antivirus products and tell you the results of each antivirus.

Level of Detection

Antivirus has different detection rate, where the virus definition and heuristic is also involved in this case. Some antivirus companies may have a more effective heuristic and release more virus definition than its competitors, so it makes the level of detection higher.

Some organizations conduct routine testing of multiple antiviruses to compare in order to get the level of detection when used every day. One of them is AV-Comparatives who frequently perform antivirus testing to compare the level of detection. Bitdefender nominated as Best Antivirus 2016. The level of detection tended to fluctuate from time to time, there is no consistent product.

How to Test Antivirus Software

If you want to test whether the antivirus is working properly, you can test it using a few lines of script. We has shared an article entitled Is Your Antivirus Guarded Yet? Here’s How to Test it! You can test your antivirus to perform the steps given in the WinPoin’s article. Relax, the script was not actually harmful, but antivirus software will detect it as a danger. You can immediately remove it when you’re finished testing the antivirus.

The computer has multiple layers of security and antivirus took part in the layer. It protects the computer by checking all the files; make sure there are no suspicious files that could harm the user or computer. Hopefully with the explanation on how the antivirus works above, it can help you understand about antivirus.

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