Now that personal computers have been a part of everyday life for about 30 years, computer viruses aren’t as mysterious as they once were. Simply put, a virus is a kind of malware that has the ability to replicate itself. Once activated, it can install itself on a computer, infecting the PC and enabling the virus to continue to spread to other computers.
Depending upon its payload, the virus can have no other effect on the PC other than copying itself, or it can be designed to cause a wide variety of damages anything from holding the files on the computer for ransom (this is called ransomware) to deleting files, crippling Windows, or turning the computer into a resource for hackers to conduct distributed denial-of-service (DDoS) attacks.
What you need to know about computer viruses
- Boot sector virus: A boot sector virus can take complete control of your PC by infecting the part of the hard drive that has startup instructions.
- Polymorphic virus: This kind of virus is especially insidious because it can vary its code, making it hard for antivirus software to detect and remove. Modern antivirus software is pretty good at detecting polymorphic viruses but is far from perfect.
- Web scripting virus: This virus specifically targets vulnerabilities in web browsers, but the virus doesn’t stay there — it can be designed to affect all aspects of your computer.
- Macro virus: Thankfully less of a threat than it once was, macro viruses are written in the “macro” language used to create scripts within programs like Microsoft Word and Excel. When a document with an infected macro is executed, it can do many malicious things to the PC.
- File infector virus: These viruses have the ability to inject malicious code into other programs and documents.
How to spot signs of a virus
The symptoms of a computer virus can vary dramatically because not all viruses are engineered to do the same thing. But if you are concerned you are infected with a virus, here are some things to watch for:
Your computer’s performance has suddenly changed
If your PC runs much more slowly than it used to, a virus can be using your PC’s resources.
Your computer has started to crash frequently
Many viruses are poorly written and can cause a lot of unexpected crashes and failures.
Lots of pop-up windows
You might start to see unusual pop-up windows in your web browser or elsewhere. They might be requests to go to websites, or your browser might open windows to other websites without your permission. Ironically, many viruses also open pop-up windows asking you to install antivirus software, which is additional malicious software.
New programs are running on your PC
You might see programs you don’t recall installing starting up with Windows.
Your email account is sending unrequested emails to your contacts
This is a sign the virus is trying to replicate itself through your contacts.
