In everyday conversation, the term “computer virus” is often used as a general “catch-all” for all computer nasties. Technically, however, the general term of malicious software is “malware” and viruses are just one specific form of malware.
The reason why this type of malicious software is called a virus is that it behaves in essentially the same way as a human virus. The aim of a virus is to replicate itself and spread from host to host, causing problems everywhere it goes.
Just as regular viruses work by attaching themselves to legitimate cells, so computer viruses work by attaching themselves to legitimate code, meaning either programs or documents which contain macros. Also like regular viruses, computer viruses can lie dormant (and hence potentially undetected) until the right circumstances arise and the malicious code is triggered.
The only common feature of computer viruses is that once they are triggered, they can spread very quickly from computer to computer. Otherwise, there is a wide range of issues they can cause.
The earliest computer virus was actually developed to be a fun way to illustrate the concept of mobile applications. It became known the Creeper virus because it just displayed a message saying “I’m the creeper, catch me if you can!”.
At the other end of the scale, there is the WannaCry virus, which made a lot of people want to cry after it rampaged across the world in 2017. There are a range of estimates about its economic impact but the lower-end estimates run into the hundreds of millions of US dollars and the upper-end estimates run into billions of US dollars.
Viruses can be subdivided into certain common types
Worms can self-trigger the replication process (rather than needing the user to take action. Possibly the most notorious worm in IT history (so far) is the iloveyou worm, which was the email plague of the year 2000.
Trojans trick the user into taking the action needed to allow them to begin their replication process. Trojans are often disguised as antivirus programs, which is why it’s really important to buy your antivirus from a reputable vendor such as Comodo.
Ransomware is a specific form of Trojan virus which encrypts files so that the user has to pay a ransom to get access to them again. It may also encrypt or delete backups, if they are on a device attached to the computer, such as a portable hard drive.
There are many other forms of malware, which aren’t actually viruses
Adware is now somewhat notorious. It bombards the victim with unwanted and possibly dangerous adverts.
Malvertising is the use of legitimate adverts as a way to deliver malware. A standard approach is to instruct the user to click on a link in the advert and this either installs the malware or directs them to a malicious website.
Spyware is pretty much what it says. It became notorious as a way for people to check on personal connections but is now often used in targeted attacks by cybercriminals.
There is also a growing trend of using a “mix-and-match” approach to creating malware, taking elements of different types of threats and putting them together. Added to this, there is no a high (and growing) percentage of what is called “fileless malware”. This isn’t a specific type of malware, it’s just a reference to the fact that it does not spread through the file system as traditional malware does, instead it may spread through memory or by using parts of the operating system such as registry keys, APIs and scheduled tasks.
Modern viruses and malware target data not devices
Viruses and malware are feared because of the damage they can do to data. Losing access to work such as student papers or business projects is only the tip of the iceberg in terms of the havoc they can cause. A virus can literally compromise your whole identity and leave you scrambling to replace everything from your bank card to your driver’s license. Then there’s the possibility of you passing them on to someone else. Even if there are no legal repercussions to this, you still have to live with the knowledge that you open up someone else to compromise.
Prevention is massively better than cure
If you are currently relying on inbuilt security programs such as Windows Defender, XProtect and/or Play Protect, then you really need to up your game. As a minimum you need to download a reputable free antivirus program, but really, given the level of risk and the possible consequences, it’s very much recommended to invest in a paid-for antivirus product which will give you the protection you need and, fortunately, Comodo has a great antivirus product at a very budget-friendly price. Head over to the Comodo website to get it now and be sure that you are safe online.
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