subject: Computer Virus-an Enemy Around You [print this page] In 1983, Fred Cohen coined the term "computer virus", postulating a virus was a program that can infect other programs by modifying them to include a possibly evolved copy of itself. Computer viruses, as we know them now, originated in 1986 with the creation of Brain - the first virus for personal computers. Viruses can infect certain types of data files, specifically those types of data files that support executable content, for example, files created in Microsoft Office programs that rely on macros.
Compounding the definition difficulty, viruses also exist that demonstrate a similar ability to infect data files that don't typically support executable content - for example, Adobe PDF files, widely used for document sharing, and .JPG image files. However, in both cases, the respective virus has a dependency on an outside executable and thus neither virus can be considered more than a simple proof of concept. In other cases, the data files themselves may not be infectable, but can allow for the introduction of viral code. Specifically, vulnerabilities in certain products can allow data files to be manipulated in such a way that it will cause the host program to become unstable, after which malicious code can be introduced to the system. These examples are given simply to note that viruses no longer relegate themselves to simply infecting program files, as was the case when Mr. Cohen first defined the term. Thus, to simplify and modernize, it can be safely stated that a virus infects other files, whether program or data. Computer viruses are called viruses because they share some of the traits of biological viruses. A computer virus passes from computer to computer like a biological virus passes from person to person. A computer virus is a program that replicates. To do so, it needs to attach itself to other program files and execute whenever the host program executes. Beyond simple replication, a virus almost always seeks to fulfill another purpose: to cause damage. Called the damage routine, or payload, the destructive portion of a virus can range from overwriting critical information kept on the hard disk's partition table to scrambling the numbers in the spreadsheets to just taunting the user with sounds, pictures, or obnoxious effects. It's worth bearing in mind, however, that even without a "damage routine", if viruses are allowed to run unabated then it will continue to propagate--consuming system memory, disk space, slowing network traffic and generally degrading performance. Besides, virus code is often buggy and can also be the source of mysterious system problems that take weeks to understand. So, whether a virus is harmful or not, its presence on the system can lead to instability and should not be tolerated.
So if you want to protect your computer from virus attack, there are several things you can do. Firstly, you should install useful and excellent anti-virus software and scan your computer at least one time a week. Secondly, you should backup your important files with unmatchable data recovery software, such as Earthsoft Data Recovery. At last, you should update your computer system and makes it clear and safe.
