There are at least <A HREF="http://news.zdnet.com/2100-1009_22-5954385.html?tag=zdnn.alert">three new variants of the Sober worm</A> spreading across the Internet via e-mail messages. The viruses are activated once a user clicks on an infected attachment. The new variants of Sober, a worm that first appeared in 2003, are capable of disabling antivirus programs, according to Finland-based company F-Secure. Antivirus company Kapersky Lab said on its Web site that large numbers of infected emails have been intercepted. This confirms, according to the company, that the epidemic was caused by spamming. Kapersky identified the variants as Sober.u, Sober.v, and Sober.w.