Virus hoaxes are reports of non-existent viruses.

Hoaxes are usually in the form of emails that do some or all of the following:

• Warn you that there is an undetectable, highly destructive new virus. 
• Ask you to avoid reading emails with a particular subject line, e.g. Budweiser Frogs. 
• Claim that the warning was issued by a major software company, internet provider or government agency, e.g. IBM, Microsoft, AOL or the FCC. 
• Claim that a new virus can do something improbable, e.g. The A moment of silence hoax says that “no program needs to be exchanged for a new computer to be infected”. 
• Use techno-babble to describe virus effects, e.g. Good Times says that the virus can put the PC’s processor into “an nth-complexity infinite binary loop”. 
• Urge you to forward the warning.

If users do forward a hoax warning to all their friends and colleagues, there can be a deluge of email. This can overload mail servers and make them crash. The effect is the same as that of the real Sobig virus, but the hoaxer hasn’t even had to write any computer code.

It isn’t just end users who overreact. Companies who receive hoaxes often take drastic action, such as closing down a mail server or shutting down their network. This cripples communications more effectively than many real viruses, preventing access to email that may be really important.

False warnings also distract from efforts to deal with real virus threats. Hoaxes can be remarkably persistent too. Since hoaxes aren’t viruses, your anti-virus software can’t detect or disable them.