Telia blocks spam-sending Zombie PCs

Trojans nipped in the bud

TeliaSonera, the leading telecommunications group in the Nordic and Baltic regions, will start to immediately block Internet traffic to and from computers that send junk email or spam, the company announced yesterday.

In order to prevent the rapid spread of spam and virus mails, the company will block all Trojan-infected PCs without warning. TeliaSoneria is the first ISP in Europe to take such drastic measures.

So far, most ISPs have only blocked Internet traffic to certain PC ports. In the UK NTL last month started blocking port 135 traffic on its Internet service. Port 135 is generally used for connections to Microsoft Exchange servers on corporate networks, but it was also compromised by the Welchia and Blaster worms.

A PC that is infected with a Trojan can send more than 100,000 spam messages or viruses in a single day. A time lapse of two weeks between the discovery and blocking of computers that send spam is therefore no longer acceptable, TeliaSoneria says. The company emphasises that it is not blocking computers on a permanent basis. Telia will offer assistance to solve the problem and then remove the blocking procedure afterwards.

Whether it will prevent a complete swamping or inundation of viruses remains to be seen. The recent Sobig.F mass-mailing virus carpet-bombed the Internet, causing chaos on corporate networks. Shutting down access to all these computers at the same time may not be possible.

TeliaSonera says that the number of customer complaints related to spam and computer viruses has increased ten-fold from 300 to 3,000 every 24 hours, and that something needs to be done. "The Internet is easy to use, but this constant flood of spam that we are now witnessing is creating costs and problems for our customers and we won't accept it,' Marie Ehrling, head of TeliaSonera Sweden, says.

John Leyden adds: Telia is taking a bold step but the policy should pay off, so long as the company correctly identifies infected machines and is responsive to customer requests to disinfect their PCs. A free AV tools such as AVG from GRISoft is one of the more straightforward ways to clean-up infected machines. We trust Telia's good sense will prevail in temporarily allowing the infected onto the Net to download updates.

Alternatives, which normally involve using RegEdit to delete viral changes to infected PCs, are hazardous.

Meanwhile what is Telia doing to put its own house in order?

Since March, Telia has used the Mail Abuse Prevention System (MAPS) to block email from known senders of electronic junk mail. In addition, Telia plans to introduce general protection against viruses in both incoming and outgoing mail, as well as protection against spam in email that is addressed to receivers outside its network. ®