Microcomputers are especially vulnerable. The widely established standards of microcomputer software make viruses easier to distribute. The introduction of a virus into a single microcomputer in a network can result in the infection of the entire system. There is microcomputer virus screening software on the market that promises to protect computer systems against infection. This software impairs any writing to a protected file.
Any preventive software can only protect against known viruses.
A prohibition of non-firm personnel using the firm's computer resources monitored by means of an alarm system acknowledging unauthorized usage. Unauthorized copies of software can cause legal problems as well. Copying files or programs should be prohibited. All software brought in to the firm to be used on stand alone or network computers should be fully tested on its own before use. Computers should be locked when not in use.