What Are the Disadvantages of Antiviruses?

By Rhonda McDowell

Whether it's a home desktop computer, college laptop or that terminal at your office, the use of a PC is part of life today. Unfortunately, so are computer viruses. As "UK Cheap Broadband" magazine advises, even if you don't download anything from the Internet, don't think you're safe from viruses or spyware. The latest viruses are designed to travel from one computer to another across the Internet, on their own. Having antivirus software is therefore a must, but you should know their possible disadvantages before settling on one.

Limited Detection Techniques

There's more than one way to detect a virus, but one big disadvantage to some antivirus programs is that they may not employ all detection techniques. According to Oracle ThinkQuest education foundation, virus scanners are the most common method of detection. Scanning means searching your computer for known virus code patterns. There's an inherent weakness here. A scanner can either give a false alarm if a pattern code happens to match part of a normal file's code. Worse, it might not detect the code of a new virus at all. To avoid this, an antivirus program's virus database must be periodically updated.Another technique is detecting changes made in files, especially executable (*.exe) files. Programs adopting this technique are called cyclic redundancy check (CRC) scanners. However, a CRC scanner can only detect changes if it already has information on what your computer's files and operating system are supposed to be like. In other words, viruses already on your computer prior to installation of an antivirus program won't be visible. The best antivirus software uses both described techniques, and supplements them with verifiers and heuristic analysis. A verifier program gives an in-depth analysis of any detected virus code, in order to ascertain if it is a virus. A heuristic analysis, on the other hand, will detect or confirm the existence of viruses by looking for symptoms or characteristics of virus behavior in your computer. Without such supplemental techniques, a virus may escape detection.

Doesn't Fully Protect

Having an antivirus program with multi-detection methods isn't enough. To avoid viruses, Microsoft Security recommends putting up an Internet firewall as well. A firewall is usually a program that blocks the hackers, viruses and spyware on the Internet from getting into your computer. You can also use hardware -- like a router -- to reinforce the firewall, especially if you use more than one personal computer to access the Internet, or have a small network of computers.

Slows Down PC or Network

Installing and running antivirus software can use up a lot of computer memory and hard disk space, slowing down your PC. StoreTech Systems Inc. mentions this is even true for protecting servers and a network of computers from viruses. Depending on how a company's management information system (MIS) or information technology (IT) personnel set up antivirus scanning and protection, the process of scanning may cause lag in the network service for individual employee-users.


Since they aren't equally effective, you may be tempted to install more than one antivirus program. Be careful, for as Symantec's ConjunGo site says: these programs may actually conflict with one another and not work properly. You'll have to either stick to one brand, or double-check for possible conflicts before purchasing a secondary program.