Sobig-A, the first in a run of six variants, hit the wild a year ago today, Jan. 9. The malicious family would go on to be known as the fastest-spreading and the most financially damaging virus in the history of computers. It also one of the earliest pieces of code to mix a virus with spamming.
Sobig-F, which ran rampant across the Internet in August and early September, has gone down in the history books as the most damaging virus to date. It reportedly caused $36.1 billion in damages.
At this point, MessageLabs, an anti-virus company based in New York, has intercepted 737,125 copies of Sobig in 183 countries. At its peak, one in every 17 emails stopped by MessageLabs contained a copy of Sobig-F, the most malicious of the variants. By Dec. 1, more than 32 million emails containing the virus had been stopped by the company, easily putting Sobig-F at the head of various Top 10 Viruses list for 2003.
Sobig is a mass-mailing worm that can also spread via network shares. When it arrives via email, the worm poses as a .pif or .scr file. The sender's address is spoofed. The worm also has updating capabilities and will attempt to download updated versions when certain conditions are met.
The Sobig variants were hitting the wild in fairly fast succession. Each variant carried code that would kill the virus off on a certain date, specifically limiting the variant's lifecycle. Soon after one variant died off, another one would emerge to take its place, building on the impact of its predecessors.
Earlier variants of Sobig infected computers and then downloaded Trojans to set the machines up to be hidden proxy servers. With each variant, the author had a bigger army of machines set up for the next seeding.
After Sobig-F died out on Sept. 10, anti-virus and security experts were waiting with baited breath for the next variant, or Sobig-G, to hit within a matter of days. It didn't, and it still has yet to hit the wild.
''I am fairly surprised about that,'' says Chris Belthoff, a senior security analyst at Sophos, Inc., an anti-virus company based in Lynnfield, Mass. ''It could be that the author or authors of Sobig are running a little scared. It was such a widespread and damaging virus, and now he has the Microsoft bounty on his head. This person or persons may be lying low out of fear. He might have been too successful for his own good.''
Microsoft Corp. announced in November that it is putting a quarter-of-a-million-dollar bounty on the heads of the virus writers behind the highly destructive Blaster and Sobig worms. The rewards are part of a $5 million fund that Microsoft set aside to battle malicious code and the hackers and spammers behind it.
But just because the author of Sobig may be laying low right now, it doesn't mean that the security industry isn't waiting for the next destructive variant to hit.
''We're always waiting,'' says Belthoff. ''We're always expecting that one day it will appear in our lab. We're always on guard.''