Not all computer viruses behave, replicate, or infect the same way. There are several different categories of viruses and malware. Below I list and discuss some of the most common types of computer viruses.
A computer virus is a computer program that can replicate itself and spread from one computer to another. The term “virus” is also commonly, but erroneously, used to refer to other types of malware, including but not limited to adware and spyware programs that do not have a reproductive ability. (Wikipedia)
A trojan horse program has the appearance of having a useful and desired function. While it may advertise its activity after launching, this information is not apparent to the user beforehand. Secretly the program performs other, undesired functions. A Trojan Horse neither replicates nor copies itself, but causes damage or compromises the security of the computer. A Trojan Horse must be sent by someone or carried by another program and may arrive in the form of a joke program or software of some sort. The malicious functionality of a Trojan Horse may be anything undesirable for a computer user, including data destruction or compromising a system by providing a means for another computer to gain access, thus bypassing normal access controls.
A worm is a program that makes and facilitates the distribution of copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism. The worm may do damage and compromise the security of the computer. It may arrive via exploitation of a system vulnerability or by clicking on an infected e-mail.
A virus which attaches itself to the first part of the hard disk that is read by the computer upon bootup. These are normally spread by floppy disks.
Macro viruses are viruses that use another application’s macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents.
Memory Resident Viruses:
Memory Resident Viruses reside in a computers volitale memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after it’s initiating program closes.
A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. The term rootkit comes from the linux administrator root user. These viruses are usually installed by trojans and are normally disguised as operating system files.
A polymorphic virus not only replicates itself by creating multiple files of itself, but it also changes it’s digital signature every time it replicates. This makes it difficult for less sophisticated antivirus software to detect.
Logic Bombs/Time Bombs:
These are viruses which are programmed to initiate at a specific date or when a specific event occurs. Some examples are a virus which deletes your photos on Halloween, or a virus which deletes a database table if a certain employee gets fired.
11 Ways to Prevent Computer Virus
It doesn’t matter if you’ve been on the Internet for five minutes or five years, you’ve probably thought about ways in which you can prevent a computer virus from entering your machine. A virus can compromise your personal information and even destroy your computer completely. Luckily, there are many low cost things you can do to protect yourself and stay one step ahead of the hackers. Here are 11 things you can do to help prevent computer viruses from invading your computer.
1. Install a reliable anti virus program – From the first moment you turn your computer on, you should have a trusted anti virus program by your side. Even if you have a machine that isn’t hooked up to the Internet, a reliable anti virus program is a low cost and common sense addition to any machine. There are even free anti virus programs you can download that work almost as well as industry giants like Norton and McAfee.
2. Install anti-spyware and anti-malware programs – As good as the best anti virus programs are, they sometimes need a little bit of help. Thankfully, many of the top anti-spyware programs are completely free. Spybot Search and Destroy and CCleaner are just two free programs that can help prevent computer viruses from doing any damage on your machine. As helpful as these programs are, however, you must update them and run them on a regular basis for them to do any good.
3. Avoid suspicious websites – A good virus protection program will alert you when you visit a website that attempts to install or run a program on your computer. Many less than reputable adult websites do this, so if you get a warning, don’t go back, you may end up with a bug you can’t get rid of.
4. Never Open Email Attachments Without Scanning Them First – The most common way viruses are spread throughout the Internet is still via email. Some attachments, like pictures, now display in emails and don’t require an attachment to be manually opened, but other documents do. Make sure you use an email client that scans all email attachments before you are allowed to open them. This will help prevent computer viruses from getting a foothold on your machine.
5. Set up Automatic Scans – Many of the top anti virus programs, as well as the best anti-spyware programs, now have settings that will let them automatically run during down times or in the middle of the night. Of course, your computer must be on for this to happen, but having daily scans run when nothing else is going on is a great way to prevent even the latest computer viruses from sticking around too long.
6. Watch Your Downloads – Part of the fun of the Internet is downloading music, movies and other items. However, since these downloads are so massive, it can be easy to sneak a virus along for the ride. Only download these files from trusted sites that you can count on, or, at the very least, scan them before you open them.
7. Updates, Updates, Updates – There is a reason why Windows has a feature called Critical Updates. There is an entire branch of Microsoft dedicated to staying one step ahead of the hackers out there so when they manage to fix a possible security loophole, you need to download the patch right away. Help Microsoft help you prevent computer viruses from causing too much trouble.
8. Know What To Look For – Even if you are just a casual computer user, you should have an idea of how your machine operates, what normal pop up windows look like and what popular viruses are out there, that way, when your computer begins exhibiting tell tale signs, you’ll know. You can help prevent computer viruses by staying updated and educated.
9. Stay Away From Cracked Software – It is so secret that you can download illegal, cracked versions of some programs online. As tempting as it may be, these files are almost always infested with advanced and difficult to detect bugs. Play it safe and get your software from the source.
10. Install a Firewall – A firewall is a program that screens incoming Internet and network traffic. Along with your virus program, it can help prevent unauthorized access to your computer.
11. Be prepared to Lock Down – If you hear of a virus that is spreading like wildfire through the Internet, make an extra effort to be careful. Don’t open any suspicious emails or accept any downloads for a week or two until your virus protection program has been updated and you are, once again, safe.
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