A new variant of the infamous Mimail worm attempts to knock anti-spam websites off the Net.
Mimail-L typically spreads as an attachment (wendy.zip) to a pornographic email claiming to come from a woman called Wendy.
Windows users who run an infectious file (for_greg_with_love.jpg.exe) within the compressed attachment get a compromised PC and not the compromising pictures promised by the email.
Mimail-L is spreading but to a lesser extent than previous Mimail variants, which have dominated lists of top Net nuisances in recent weeks.
If Mimail-L is activated, the worm forwards copies of itself on to other email users, and reprograms computers to launch a denial of service (DOS) attack against websites run by spam fighting organisations. Sometimes, but not always, the virus spoofs the email address it appears to come from to 'wendy@' a recipient's domain.
Anti-spam websites on the virus's list for a denial of service attack include those operated by SpamCop, SPEWS and The Spamhaus Project. Other websites targeted include Disney's Go website.
The actions of Mimail-L are much like those of a previous variant of Mimail which also attempts to DDoS anti-spam sites.
If, for any reason, Mimail-L fails to propagate correctly it sends an alternative email (without a viral attachment) claiming that the recipient's credit card details have been debited, and that a selection of child porn CDs will be delivered via the post. Users are given the email address of a reputable anti-spam organisation if they wish to 'cancel' this bogus order.
"This worm wages war on the anti-spam community, disrupting their attempts to keep the net spam-free, said Graham Cluley, senior technology consultant for Sophos. "The writer of this worm seems to have a grudge against anti-spam Web sites and the suspicion has to be that this person is a spammer or is working in collusion with spammers."
"We can't be certain, but all the variants of Mimail seem to come from the same individual or group of virus writers."
Standard defence precautions apply against viral attacks from all variants of the worm: users should update their AV signature definition files to detect the virus and resist the temptation to open suspicious looking emails. ®