The virus spreads itself by sending itself to all e-mail addresses it finds on the computer of its victim. Anti-virus firm MessageLabs rates it as a high outbreak as they have caught more than 850,000 copies by Wednesday.
Bagle first appeared in early 2004 and there are now more than 70 variants of this worm. The new Bagle variant tries to out-fox anti-virus firms by downloading new variants of the virus. The first variant was spotted around 1.30pm GMT on Tuesday and a new version came out one hour later. Since then new variants are released every half hour. This creates a huge overload for anti-virus firms.
The purpose of producing variants is to overload anti-virus firms, and has been seen before. But the timing of them so that they go together with anti-virus firm updates, is new, according to Mr Schipka.More info at BBC