omputer virus protection is a basic security measure that agencies need to implement. Viruses are unwanted computer instruction sets that covertly attach to and spread among programs and documents, with the goal of altering how a computer works. At their least destructive, they may change screen displays or slow down a machine; at their worst, they may erase the hard drive.
Viruses spread through a number of channels, which include sharing floppy disks, downloading files from the Internet, and through e-mail attachments. Early warning signs include slower PC operation, programs failing to start, or unusual error messages.
Anti-virus software protects against viruses by scanning your computer for the signatures, or strings of zeroes and ones, that identify known viruses. Some of these software tools reside on your computer and continuously check for virus signatures or virus-like actions. Some even remove the viruses.
Over the years, virus creators have invented strains that are harder to detect. Encrypted viruses, for example, consist of an encrypted virus body and a decryption routine; the virus is scrambled at each infection, hiding its signature. However, the virus' decryption routine remains the same, so scanners were developed to search for the signatures of known virus decryption routines. Next came polymorphic viruses that scrambled both the virus body and the decryption routine. New virus detection methods countered this by systematically loading files into virtual computers created within the computer's memory. Once there, a virus would decrypt itself and expose itself to the anti-virus software's scanning capabilities. The biggest problem today for anti-virus tools is posed by macro viruses, which reside in template or macro files for Microsoft Word documents.
Anti-virus software packages can be installed on any type of computer, although experts recommend concentrating on individual desktop computers or laptops. Packages are available from companies such as Symantec Corp., McAfee Associates, IBM Corp., Norman Data Defense Systems Inc. and S&S International. It's imperative to have current versions of the software, as new viruses are discovered on a regular basis; some new anti-virus software automatically downloads updates from the Internet.