What are the computer viruses and how do they work?

Computer viruses were the dominating malware class for almost a decade. Now they are very rare. How could that happen?

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Computer viruses - the tribute to history

What is a computer virus?

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Computer virus is a definition that confuses a lot of people. Some think of it as the definition of malware at all, but they are wrong. Hence, it is important to show what a computer virus is.

History of computer virus

Computer viruses were the one of the firstlings in the malware world. First widespread malware was, exactly, the Creeper virus. It was created by Bob Thomas and designed to infect a DEC PDP-10 - one of the most massive computers of that time (1971). Mr. Thomas created it without any malevolent intent - just to show his colleagues how such programs work. However, the Creeper virus was doing the same thing his modern brothers-in-arms do - replicating his code into other programs. That led to making the inflated programs malfunction and the hard disk overflow.

Creeper virus
The message Creeper virus was displaying on the infected computers

Virus did not become a massive malware instantly. Just as any other malware, it was struggling to become massive because of the spreading problems. Sure, it's quite easy to infect the computers in your uni’s campus, but almost impossible to do that in other places. Until the wide spreading of the Internet connection viruses were distributed on floppy disks - together with multiple other programs.

In the ‘00s, after the Internet boom, viruses became one of the most widespread malware types in the whole world. At that time, people started calling all malware the viruses - just because the chance that it really is a virus was very high. Low cybersecurity knowledge, weak system security and absence of automated ways to remove that lead to the situation when having your computer infected was almost normal. That pushed the development of programs that we know nowadays as anti-viruses.

So what is the computer virus?

Computer virus, as it was mentioned in the paragraph above, is a malware that replicates its code into other programs and files. Then, this replicated part starts replicating itself into other files, so the destruction goes exponentially. At one moment, the program stops working as usual, and may even fail to start. Finally, it may turn out that your computer fails to do even a thing without calling the error window. In the baddest cases, when the virus damages critical system files, you will see the BSOD when trying to boot Windows.

Virus mechanism
That is how viruses work

What is more interesting - viruses were completely unprofitable during this boom. For sure, in ‘00s there were a pretty low number of malicious programs that could be monetized in any way, but it is very unusual to hear now, in 2022. In those days, malware was rather distributed to have fun, or to mischief someone than to gain money. And, in fact, the end of the computer virus domination era was the start of the malware-for-profit epoch, which lasts till these days.

Why did computer viruses disappear?

It is pretty ironic that computer viruses were the stimulus for anti-malware programs to be created, and exactly anti-malware was the force which made the viruses cease to exist. Malware analysts had an enduring combat with viruses for a decade, but finally found the way to stop them all - even the newest ones. They implemented the rule “if it reads a text as a code - it is a virus” - and that was enough to make all attempts of malware creators useless. And they possibly could be more motivated if their job was profitable, but that was much more reasonable to switch on other malware types, or even go to white job.

Sure, viruses did not disappear completely. It is possible to bypass the aforementioned rule by some tricks with obfuscation and repacking. However, there is still no way to monetize a stand-alone virus. It makes the programs as well as system malfunction - and what’s next? It is quite hard to try to make money on that thing, but crooks still use it sometimes. Viruses are pretty useful when you need to exploit the vulnerability, or to make the certain apps malfunction. That’s why cybercriminals sometimes apply using specially created viruses for committing cyberattacks on corporations.

Obfuscated code
Code obfuscation allows malware to bypass the check of anti-malware heuristic engines

Computer virus distribution

In old times, when computer viruses were on the malicious Olymp, viruses were literally everywhere. You could click on the banner online and get one, install a pirated game - and the virus will be included. Even visiting certain websites was not safe - viruses were able to stealthily get on your PC and launch. Needless to say that most of these spreading ways are not possible in modern times - just because the software has a much higher level of protection. Yes, malware developers may say for sure that earlier was better.

Nowadays, as it was already mentioned, viruses are mostly used in cyberattacks. Hence, their usual spreading ways are the same as spreading ways of the initial payload for attacks on companies. Spamming of different sorts, RDP exploitation, social engineering or even all together simultaneously - all these things are typical for computer viruses spreading. After the successful penetration of the network, the virus is launched together with keyloggers or other things.

Email spam example
The example of email spam message

More interesting thing is how these viruses are designed. Since anti-malware programs have such a powerful countermeasure, it is impossible to use classic computer viruses. That’s why crooks usually order it somewhere, and receive a real Frankenstein child. Most of such malware is ordered somewhere in Asia, and then used to commit attacks on the whole globe. These viruses are packed in a very unusual way, and have an extremely obfuscated code. Such tricks allow the fraudsters to avoid the malware detection. Nonetheless, it is better to use a backdoor - it is much harder to detect, and easier to make stealthy.

How to prevent computer viruses?

Getting a computer virus these days is like finding a gold nugget in a pig trough. There is a small chance to get one when browsing some really old pages on your old computer. But if you are afraid of getting one - just forget about opening suspicious pages and starting the programs from untrustworthy sources. In fact, it is not about preventing viruses - it can help you to prevent any malware. So let’s check them out - just to stay aware.

One of the most massive sources of malware for individual users is the illegal software. Hacked games from torrent trackers, or even downloaded directly from the websites with “free” games, hacktools and keygens for various software are the best carriers for malicious software. In particular, stuff like KMSPico is considered one of the most common sources of ransomware and spyware at the beginning of 2021. Forget about using it - and you will decrease the chances to get a virus significantly.

KMSPico main screen
KMSPico program - one of the most massive sources of malware

A new trend in virus distribution is email spamming. Fraudsters send the emails that bait users to click on the link, or to open the attachment. Whatever it is, you will receive malware on your PC after the malicious script execution. Avoiding such emails is not very easy: crooks try to make them similar to the original messages from legit companies, like Amazon or Fedex. Thus, you must remember the only difference they cannot hide - the sender’s email address. Just keep in mind that delivery messages from Amazon will not be sent from fhasab36vc130@protonmail.com - they have an official and genuinely-looking email address for that case.

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And the last advice, which acts rather as a last remedy, is to use anti-malware software. The most effective way to protect yourself is to combine the additional security software and your personal knowledge. Proper security tool, like GridinSoft Anti-Malware, will definitely protect your system from computer viruses, spyware, ransomware or all other threats.