Sobig blamed for fourfold rise in spam

The amount of spam moving around the Internet has increased from one spam in every eleven emails at the end of 2002 to one spam in every 2.5 emails today; a more than fourfold increase.

According to an end-of-year report published by email-outsourcing firm MessageLabs on Monday, the Sobig.F virus is to blame for a large proportion of the increase. Before Sobig.F, spam made up less than half of all email traffic, but in the latter part of the year, in the wake of Sobig.F, spam levels pushed past the 50 percent mark, bringing the average for the year up to 40 percent.

Mark Sunner, chief technology officer at MessageLabs, said that a convergence of virus technology and spamming techniques have resulted in a large proportion of PCs being transformed into spam engines: "Sobig.F sought not only to infect a machine and propagate through mass-mailing techniques, but also to compromise systems by exploiting open proxies. This backdoor route means that an infected PC can be turned into a spam engine -- causing individual users concern, as well as (causing) security breaches."

This behaviour led to Sobig.F easily topping the MessageLabs top 10 virus list for 2003, with a massive 32,432,730 interceptions. MessageLabs predicted that as much as two thirds of all spam email is being spread via PCs that have been compromised by viruses, such as Sobig.F

Security company Sophos last week said that virus writers were either working with spammers, or were the spammers. Graham Cluley, a senior technology consultant for Sophos estimated that around a third of spam was relayed through "hijacked computers" because of Remote Access Trojans (RAT), which are files that give control of a PC to an attacker. "They can steal information, read files, write files, send emails from that user's name -- it is as though the attacker has broken into the office or home and is sitting in front of that computer," he said.

MessageLabs also said that the amount of spam it intercepts has increased from two spam emails every second, to 27 spam emails every second, over the course of the year.