The return of Sobig

The frequency of previous Sobig variant infections suggests we should be bracing ourselves for the next iteration of the fast-spreading worm any day now. Sobig has caused havoc for computer users over the past few months, but the latest variant died out on 10 September and now it is only a matter of time until the next one strikes, according to leading anti-virus experts.

Simon Perry, VP security strategy at Computer Associates, said: "Given the effectiveness of the last version of Sobig, I wouldn't be at all surprised to see a new version come out. As for timing, it is reasonable to assume that we will see one sooner rather than later."

Pete Simpson, ThreatLab manager at Clearswift, said: "Sobig was the sixth in a series of controlled experiments by the creator of this worm. We fully expect to see a seventh emerge in the very near future. The intervals between the cessation of the virus spreading and the release of a new version have varied from less than seven to more than 35 days."

Given that the last virus self-terminated on 10 September we have already passed the earliest of previous re-occurrences.