Anti-spam organisations are coming under attack from a virus written to bombard their websites with junk data.
Spamhaus: Attacked for the third time
The Mimail-L Windows virus poses as an e-mail from a woman called Wendy who writes about a sexual encounter and offers readers nude photographs.
Opening the message's attachment rewards users with a virus that forwards itself to everyone in their e-mail address book.
It also turns infected machines into junk mail relays that can be used to forward thousands of messages to one of eight anti-spam websites.
Like most other viruses, Mimail-L is aimed at users of Microsoft Windows and its Outlook e-mail program.
The Mimail-L virus also tries to harm anti-spam websites by sending an e-mail to infected users claiming that their credit card has been debited to pay for a CD full of images of child pornography.
The fake message gives a billing address that people can complain to if their card has been wrongly debited. However, this e-mail address is for the Spamhaus Project which is fighting spam rather than a child porn peddler.
"So many Internet users are flooding us with complaints about these child porn CDs that we supposedly ordered for them," said Steve Linford, founder of the Spamhaus Project.
Mr Linford said he was co-operating with the police to find out who was behind the Mimail-L virus.
He suspects that it is the work of an irate spammer, irritated at the success Spamhaus and other organisations are having defeating junk mail messages.
"They are angry with us because we try to stop the spamming cycle," said Mr Linford.
Organisations such as Spamhaus find and circulate lists of known spam organisations that helps net service firms block junk messages before they make it on to the web.
"It's the third Mimail variation to come after us," said Mr Linford, "except this one is trying to do more."
Anti-virus firms said Mimail-L was not widespread but warned people to be on their guard and keep anti-virus software up to date.
Other variants of Mimail target other websites with junk data attacks. Previous versions of the virus tried to steal credit card information.