Computer 'viruses' are a serious threat to all computer systems, particularly systems linked in networks and systems connected to the internet and to email services. Virus protection software is an essential part of any modern computer system.
What is a computer virus?
Computer viruses are programs developed by mischievous or malicious computer programmers that are capable of performing a wide range of functions on 'infected' computers, from the benign to the malign.
Benign viruses can simply perform harmless (but usually annoying) functions such as displaying a pop-up message. Malign viruses can corrupt or change data or programs, destroy computer files, or cause massive amounts of email to be generated, threatening the stability of networks by swamping them with data.
Viruses are spread by transferring infected files from one computer to another. This can happen by transferring files on removable data disks, by accessing or downloading files on the internet or a network, or by files sent by email. Viruses can be executable files (with a '.exe' filename extension) or files in other formats, such as word processing files containing macros. Running these executable files or opening files containing infected macros can cause a computer virus program to run that can potentially do a great deal of damage.
Some viruses attack email programs. By accessing a user's list of stored email addresses, a virus can self-replicate itself by sending copies of the virus to each email address. The multiplying effect of this strategy means that a virus can spread to a large number of computers all around the world in a short space of time.
Computers hit by a virus attack can be severely damaged, and a lot of data can be lost or compromised. In the worst cases a computer's hard disk can be rendered useless, and all data on it lost. In these cases the best that can be done is to reformat the hard disk (wipe it clean and start again) and reload all the necessary software from backups.
The possibility of a virus attack is a very powerful incentive to conduct regular, thorough backups of programs and data. (See Ensuring Availability of Data for more detail on backup procedures.)
Virus protection software
The way to protect a system against a virus attack is to use virus protection software. Virus protection software is designed to run on a computer at all times in the background, so that the user is usually not aware of it unless a problem arises. Virus protection software is designed to recognise known viruses and prevent them performing their intended functions.
In addition, as new viruses appear frequently, virus protection software is also designed to identify the possible activity of a virus and prevent it from functioning. For example, a typical virus protection program will place a 'tag' on each known executable file on a computer. If an unknown executable file attempts to run a program, the virus protection will sound an alert and ask the user whether the user wishes the program to run. If the user confirms that the executable file appears to be a virus, the virus protection software can delete the virus from the system.
Unfortunately, as new viruses take new approaches, virus protection software has to play a continual game of 'catch-up' as each new virus is identified. As a result, virus protection software has to be frequently updated to ensure that it is capable of identifying and dealing with the latest known viruses. A structured regime for updating virus protection software can be part of an EMBs technology strategy.
Safe computer practices
Regardless of the presence of virus protection software, some viruses can still escape detection and infect a computer system. In order to guard against this possibility, data should be regularly backed up and users should be taught 'safe computer practices'.
Because of the possibility of viruses, all users should be aware of the steps necessary to avoid catching one. First, virus protection software can be installed and running, not disabled. Systems administrators will often want to monitor virus software operation to ensure that users have not disabled their virus protection, or better still, users can be restricted from disabling their virus protection.
Second, users will need to be careful about opening files and particularly running executable programs if they are not sure that they are legitimately sent by a known source. Even emails from known contacts can be suspect, as viruses can control a user's email contact list and send messages using any name on the list.
Viruses sent by email can be accompanied by plausible and enticing messages that might encourage users to open the infected files. Users need to be cautious of such approaches.
If users are not confident that files or programs sent to them are legitimate they should not open them. If the files or programs appear to be inconsequential, they can be deleted (and remember to also delete them from the 'recycle bin'). If the user is not sure whether a file or program is legitimate, the sender can be contacted to verify that the file or program is genuine.
When in doubt, a user will want to contact the relevant help desk or technical assistant for advice.
