Computer Viruses

Explain the difference between viruses, worms and Trojan horses in the context of computer and data security. Discuss the measures that need to be taken in order to maintain security.

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There is a type of computer program that is designed and written to destroy, alter or damage data stored on computers without your knowledge or permission. These are some of the problems that these programs cause

? Your computer displays annoying messages

? Your computer develops strange visual and sound effects

? Files on your computer mysteriously disappear

? Your computer starts working very slowly

? Your computer reboots unexpectedly

These programs are typically referred to as viruses although technically the computing term virus actually refers to a specific type of pest program. Other types are called Trojan horses and worms. The difference between these pest programs is how they behave when attacking a computer system and I am going to look at each type individually to explain the difference starting with viruses.

A computer virus is a program that is designed to replicate and spread itself on its own, preferably without anybody knowing it exists. They spread by attaching themselves to other programs (such as your word processing or spreadsheet programs). Then when a file with a virus attached to it is executed the virus will also be executed. Viruses can also attach themselves to system files the computer uses every time it is switched on, these are called boot sector viruses, and can cause persistent and widespread disruption to the computer. Viruses can also infest documents such as those created with a word processor. Infested documents are stored with a list of instructions called a macro, which is essentially a mini program. Then when the document is viewed the macro is activated. These viruses are called macro viruses and actually account for 67.5% of all virus damage.

Worms are very similar to viruses but are technically different in the way that they replicate and spread through the system. The difference is that programs or files don t need to be run in order to activate the spreading of a worm. Because of this worms can be very dangerous when released on to computer networks. The Internet Worm was released on to the Internet on the 2nd November 1988 spread to over 6,000 computers in less than a day. And the total monetary costs of this infection are estimated at about $98,000,000. Which proves how much damage can be done with a worm. The final type of pest program is a Trojan horse.

A Trojan horse is a malicious program that masquerades as a legitimate program. It will appear to do one function while actually doing something else. For example, you might think you are opening up a compression program when you re actually running a Trojan horse which erases your hard drive. They tend to be very nasty and very difficult to detect. However they do not replicate themselves which is what separates them from a virus. A popular Trojan horse is one that masquerades as a network login screen. So when the user logs in the Trojan horse records the users ID and password so the hacker can access them at later date. With these details the hacker can then gain access to the network and any data that was thought to be secure.

There are precautions that can be taken to protect and maintain data security. You can generally avoid a computer virus if you are just careful not to use files from high-risk areas such as off the Internet. If you do need to use a file from a high-risk source then you can use a virus detection program before you run it. A virus detection program will check for viruses and if necessary eliminate the problem. Other ways of protecting data is to make frequent backups so if a virus does destroy any data it can be replaced once the virus has been removed. And finally take basic steps to ensure that there is no unauthorised access. Unfortunately, even with all these precautions it is almost impossible to ensure complete data security but they will help to reduce the risk drastically of any unlikely occurrence.