How does an anti-virus work?

in cybersecurity •  9 months ago  (edited)

The vast majority of the people who own a desktop pc these days also have an antivirus program installed on it. In fact, Windows devices comes with a built-in antivirus called Windows Defender. But have you ever wondered how does an antivirus actually work? How does it detect and identify a virus on your device and flag it as a potential threat?

Every virus or malware that is created has its own unique digital signature that helps in identifying the creator of the malicious program. Most hackers prefer generating a virus through tools without the need for extensive scripting and coding. Such kind of tools also include their signature in each and every malicious program that they create. This digital signature helps in identifying what type of virus or malware a particular program is and which tool created it.

When hackers create a malicious program, they upload it to websites and run it against antivirus scanners to see if any of the antivirus programs detects if the file is malicious or not. More often than not, these websites which perform the scans also share the signature of the virus to all major antivirus providers. Antivirus providers as the ones mentioned above, update their database regularly by adding newly identified signatures. One of the most popular website called VirusTotal is used by hackers to scan their malicious programs. VirusTotal is a company owned by Google.

When the files are uploaded to the VirusTotal website, it performs scans against numerous antivirus programs including the ones mentioned above and checks whether these programs are able to detect any malicious signatures. If the digital signature is unique, it will be not be detected by most to the antivirus programs and says that the file is “clean” or safe. The company will later verify the file once again by running it and if any suspicious activity is detected, it will record the digital signature of that program.

This is then sent to all other antivirus providers and they update their database with this signature. Thus in a matter of few hours, all major antivirus software will detect this as a potential threat and prevent that any files containing that particular signature from executing. This is how software are capable of detecting viruses and malware. Ensure that the antivirus program that you have installed on your device is up-to-date and the databases of those are also up-to-date. This will stop a great number of viruses and malware from entering your devices.

If a virus or malicious program that hasn’t been uploaded online and has been specially programmed to target you (without using tools to create the virus), then there is a good chance that your anti-virus software will not recognize it as a malicious program. But there are exceptions. Some of the anti-virus programs are starting to implement something called Behavioral Analysis. This means that the software will learn and understand how you use your systems, what programs you executes and what processes are running everyday.

If an unusual activity (behavior) is recorded over a period of few days, the anti-virus software will find the source of that activity and flag it as a potential threat. It will then analyze the behavior of that program and classify it as a virus if any suspicious activity is found. The problem with this technique is that you will get to know that your device is infected, only after a few days. Not all anti-virus providers have implemented this functionality into their program as of now. But as time goes on, more and more providers will incorporate this feature into their software.

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