Antivirus or anti-virus software is used to prevent, detect, and remove malware, including but not limited to computer viruses, computer worms, trojan horses, spyware and adware. In order to be effective, anti-virus software should be regularly updated - otherwise it will fail to give protection against new viruses.
Eradicating a virus is the term used for cleaning out a computer. There are several methods of eradication:
A variety of strategies are typically employed.
Signature-based detection involves searching for known patterns of data within executable code. Viruses reproduce by infecting "host applications," meaning that they copy a portion of executable code into an existing program. So to ensure that they work as planned, viruses are programmed to not infect the same file multiple times. To do so, they include a series of bytes in the infected application to check if it has already been infected- this is called a virus signature. Antivirus programs rely on this signature, which is unique to each virus, in order to detect them. This method is called signature based detection, the oldest method used by antivirus software. However, this method cannot detect viruses which have not been archived by the publishers of the antivirus software. What's more, virus programmers have often given them camouflage features, making their signature hard to detect, if not undetectable. To counter such threats, heuristics detection approach can be used.
One type of heuristic approach, generic signatures, can identify new viruses or variants of existing viruses by looking for known malicious code, or slight variations of such code, in files. The heuristic method involves analysing the behaviour of applications in order to detect activity similar to that of a known virus. This kind of antivirus program can therefore detect viruses even when the antivirus database has not been updated. On the other hand, they are prone to triggering false alarms.
No matter how useful antivirus software is, it can sometimes have drawbacks. Antivirus software can impair a computer's performance. Inexperienced users may also have trouble understanding the prompts and decisions that antivirus software presents them with. An incorrect decision may lead to a security breach.