Here is a list of recommendations for computer users for virus prevention and control. It was drafted by the National LAN Laboratory in Reston, Va., and approved this week by more than 60 companies: 1. All software should be purchased from known, reputable sources. 2. All purchased software should be in its original shrink wrap or sealed diskette containers when received. 3. Back-up copies of all original software should be made as soon as the software package is opened. Back-up copies should be stored off-site. 4. All software should be reviewed carefully, by a system manager, before it is installed on a computer network. 6. New software should be quarantined on an isolated computer. This testing will greatly reduce the risk of system virus contamination. 7. A back-up copy of all system software and data should be made at least once a month, with the back-up copy stored for at least one year before re-use. This will allow restoration of a system that has been contaminated by a ``time-released'' virus. A plan that includes ``grandfathered'' rotation of back-up copies will reduce risk even further. 8. System administrators should restrict access to system programs and data on a ``need-to-use'' basis. This isolates problems, protects critical applications, and aids problem diagnosis. 9. All programs on a system should be checked regularly for program length changes. Any program-length deviations could be evidence of tampering, or virus infiltration. 10. Many shared or free programs are invaluable. However, these are the prime entry point for viruses. Skeptical review of such programs is prudent. Also, extended quarantine is essential before these programs are introduced to a computer system. 11. Any software that exhibits symptoms of possible virus contamination should be removed immediately. System managers should develop plans for quick removal of all copies of a suspect program, and immediate backup of all related data. These plans should be made known to all users, and tested and reviewed periodically.