How to Protect Your Computer from Computer Viruses

A computer virus is a tiny program that alters the way that a computer functions without authorization from the user, thereby unleashing havoc on a computer's ability to operate effectively. A virus can delete and corrupt important data files, alter vital system components, and completely impair a computer's ability to function. Any computer that has been invaded by a virus is said to be 'infected.' Since viruses are computer programs, they have recognizable binary patterns. Early virus scanners from the 80s and 90s worked by identifying these binary patterns. Modern scanners go a step further by noting unusual file modifications or directory activity. A few common virus types include:

Macro

Macro viruses function by attaching to a macro file. They are most often found in databases, spreadsheets, and word-processing documents. They hide within the application's macro and are only activated once the macro is manually executed by the user.

Boot Sector

Boot sector viruses are deposited on floppy disks. When the disk is booted by a user, the virus quickly attaches itself to the computer system and begins its malicious activities.

File infector

File infector viruses contaminate executable code such as .exe. or .com files. Once the program is executed, the computer immediately becomes infected.

One form of a virus is what is called a worm. A computer worm is a specialized virus that transfers itself from one computer system onto another through the Internet without any manual human assistance. Worms typically transport themselves via a Trojan horse. A Trojan horse, in regards to computer terminology, is a damaging piece of computer code that buries itself beneath e-mails and macros. If you open an email that has a Trojan horse worm virus hiding within it, your computer will immediately become infected.

Protecting your computer from computer viruses requires purchasing an anti-virus software suite that is capable of checking your computer periodically, and quarantining or removing any malicious files. As you download files, check your email, and open applications, the anti-virus suite monitors activity and warns you about any potentially harmful threats. To ensure the most effective anti-virus activity, you should purchase a suite that offers signature, terminate and stay, and multi level scanning and monitoring.

Signature Scanning

Signature scanning works by recognizing the unique structure and pattern of a computer virus. The binary pattern, or signature, of a computer virus is very similar to the concept of DNA. It is a unique pattern inherent to only that virus. Currently, all viruses known by virus researchers and anti-virus product developers are categorized by their signature. Signature scanning uses these categorized signatures to search for and identify any viruses hidden in a computer system. Because new viruses are constantly being manufactured, you must continually (everyday) update your virus catalog. This can be done by downloading new virus information from the Internet. More often than not though, virus updates are automatically performed by the anti-virus software.

Terminate and Stay Scanning

Terminate and stay scanning allows an anti-virus suite to run continuously in the background and scan for viruses. They provide a combination of real-time scanning of disk drives and files, detailed analysis of virus-like behavior, and polymorphic virus detection. Polymorphic refers to viruses with the capability to continually mutate (thereby changing their signature) and escape detection. The advantage of using an anti-virus suite with terminate and stay capability is that the user must not manually load the software every time that he or she opens or downloads a file.

Multi Level Scanning

Multi level scanning uses a combination of anti-virus techniques including checksum analysis and system virus analysis. It applies a checksum value to any data at precisely two major times during the file's lifespan. A checksum value is applied when the file is first created or received, and then later on once the file has been in memory for awhile. The anti-virus suite will then periodically compare the original checksum value to the current checksum value. If there is any discrepancy, the file is then scanned for malicious virus activity. System virus analysis involves a sequence of algorithms that perform millions of virus tests on your computer files. A score is then assigned to each file or software application in question. If the score is a certain value, a virus scan is then performed.

Anytime that you purchase an anti-virus suite, be prepared to ask the seller whether it offers signature, terminate and stay, and multi level scanning. If it doesn't offer all three, then find a better anti-virus program. And if the seller has no clue what you are talking about, then RUN, and run fast!