All About Computer Viruses
Computer viruses are a problem that every computer user encounters sooner or later. In fact, viruses are just one example of a whole group of nuisance programs which are known as malware, for malicious software.
Types of malware include:
- Viruses - like their biological counterparts, these are programs that infect a computer (by various methods) and then spread to other computers when infected files or disks are exchanged;
- Worms - these are similar to viruses but are carried on the Internet and can spread from one computer to another by themselves, with no need for a user to assist the process by giving someone an infected file or disk;
- Trojans - named after the Trojan Horse of mythology, these are programs that pretend to be harmless and useful, but which in fact do something sinister, like plant a virus in a computer;
- Spyware - software that tracks your online activity or monitors your keystrokes and sends this information to a remote server;
- Dialers - programs that are downloaded to your computer from a web page, which then steal money from you by dialling premium rate phone numbers;
- Hijackers - programs that are usually infiltrated on to your system via email or your web browser, which then hijack your browser settings by (for example) changing your default home page setting.
Viruses, worms and trojans cause a nuisance just by spreading their infections, but most of them also do something else, known as the payload. The payload may be something innocuous, like displaying a message or changing the system colours, or it may be something destructive like deleting files or formatting the hard disk. This payload often isn't activated until the virus has infected your computer for a while (giving it a chance to spread) so the fact that you haven't noticed anything unusual doesn't mean your computer is necessarily in good health.
If your computer gets infected, whether the payload is harmful or not you want to get rid of the virus as quickly as possible, so as to remove the risk of it spreading to the computers of your friends and colleagues.
The only sure way to get rid of a virus is to use anti-virus software. Some viruses can be removed manually, but different viruses need different removal methods and by the time you've found out the correct procedure a software virus scanner could already have done the job.
In a few cases, the virus scanner may not be able to cleanly remove a virus from a file, and the file may be left corrupt and unusable. In this case, your only option is to restore an uninfected copy of the file from software installation disks or a backup.
A good backup system is by far the best safeguard against losing data due to the action of a virus (as well as other disasters). But it must work hand-in-glove with the regular use of a virus scanner, otherwise your clean backup files could be replaced by infected ones before you realise your system has a virus.
How to prevent viruses
It's better to prevent a virus from infecting your computer in the first place, than have to remove one after it has. Therefore, it's worth paying attention to virus prevention measures.
The best all-round system of protection is to install anti-virus software and enable on-access scanning (this is usually enabled by default.) This will work silently in the background, checking files for the presence of viruses. You need not worry about it until it detects a virus and raises the alert.
However, you must remain conscious of the need for virus protection to the extent of remembering to update your virus scanner regularly. These days, even daily updates may not be often enough. Products like Kaspersky AntiVirus update every hour!
Updates are extremely important. New viruses are constantly appearing, and despite the claims of software vendors, virus scanners are not very good at detecting viruses they don't know about. Updating is the only way to maintain your virus scanner at top effectiveness by ensuring it knows about, and can detect, all the latest threats.
How to avoid viruses
Even regular anti-virus updates aren't enough to completely prevent the spread of viruses, especially worm viruses. Worms are transmitted so quickly across the Internet that thousands of computers can be infected before even the anti-virus software developers are aware of their existence.
You can avoid much of the risk of infection by not using Microsoft software packages like Word, Outlook and Outlook Express. Many viruses exploit features of those packages and don't work on computers that don't use them. But if you're already using these Microsoft products, it's not so easy to give them up.
Because email is now the most common way for viruses to spread, another good approach is to filter out or block emails containing attachment types that can be used to carry viruses. Most good anti-virus products include email filters that do this automatically.
You can avoid helping to spread worm viruses by using the virus detector between your ears. Don't download software from sites you aren't sure about, and treat all email attachments with suspicion. You can easily avoid becoming infected by and spreading internet worms by following the simple steps in "How To: Detect Internet Worms".