If the checksums do not match then the file has been modified in some manner. Some integrity checkers may be able to identify the virus that modified a file, but others may just be able to aleart you to the changes. Integrity checkers are not only useful for detecting a possible infection, but also useful for helping to detect intruders. Since new viruses are created every day, it is important to keep your anti-virus product up to date. Contact information for product support is also listed.
Some vendors use email mailing lists to alert users of updates.
Often, you can subscribe to these lists through the vendors web sites. Articles The following documents about computer viruses, chain letters, and hoaxes come from various sources. This paper is a technical discussion of the CIH virus. Using encryption We strongly urge you to encrypt sensitive information sent by email. If you prefer to use DES, please call the CERT hotline for more information.