copied from ABC News

[Guest guest]

The new virus, named " Sobig.F " by computer security companies, attacks

Windows users via e-mail and file-sharing networks. It also deposits a Trojan

horse,

or hacker back door, that can be used to turn victims' PCs into senders of

spam e-mail. MessageLabs Inc., a company that filters e-mail for corporations,

had blocked more than 100,000 copies of Sobig.F by midday Tuesday, making it by

far the most active virus of the day. " It's definitely spreading very

quickly, just an incredible ramp-up so far this morning, " said Czarny,

marketing director at MessageLabs. The variant is likely to be one of the more

successful versions of a very successful virus strain, he said. The previous

Sobig.A

and Sobig.B variants are both on MessageLabs' list of the biggest 10 e-mail

viruses of all time. The e-mail message that carries Sobig.F has the subject

line " Re: Details " and the message " Please see attached file for details. " If a

recipient clicks on the attachment, which can have multiple names ending in the

..pif file extension, the computer will be infected. The virus will then send

itself out to names found in the victim's address book and will use one of

these names to forge a return address. As such, the infected party may not

quickly learn of the infection, while an innocent party may get the blame for

helping to propagate it. Like all the other Sobig viruses, this version is

programmed to self-destruct after two weeks, in this case on Sept. 10. The

Blaster worm

is still at large. It uses a published flaw in Microsoft's Windows operating

systems to spread via network connections, without using e-mail. It slowed

down the Internet and caused computer restarts worldwide, but the attack it was

programmed to carry out against a Microsoft Web site on Saturday proved

harmless.

n Rojas