No Safety in Numbers

Experts say virus writers seem to be combining efforts.

So youve started to resent all of the long hours youre putting into writing code, locking down servers and desktops, tuning that cranky intrusion detection system, and scrambling to find the user whose machine is infected with the latest virus. Well, dont worry, there are still people working harder than you: the crackers.

Writing viruses and other kinds of malware used to be a solitary pursuit. Would-be felons hunched over their keyboards, hacking out malicious code for days, either in a misguided attempt to prove their programming prowess or to unleash the furies on some remote nemesis who had done them wrong. Once the code was released into the world, it would either work its black magic, damaging PCs, deleting files and clogging corporate networks, or it would flop, going unnoticed in the chaos of the Internet.

Those were the available story arcs for most viruses and worms until recently. Now, as malware such as SoBig, Blaster, Code Red and others have shown, virus writing is starting to become a cooperative, albeit informal, enterprise. What all of these new viruses and worms have in common is that they all wreaked their share of havoc upon release, but each one was also later modified, refined and re-released, probably by someone other than the original author.

Source code is posted on underground Web sites—or sometimes on public security mailing lists—and crackers can go over it at their leisure and make whatever changes they want before sending the worm or virus back into the wild.

SoBig.F is both the latest and the most extreme example. It is the sixth version of the virus to be released, and although it is remarkably similar to its ancestors in many respects, it also includes a capability that forces infected machines to contact a remote server to download an update.

The self-updating capability that had anti-virus experts, users and the FBI scrambling was, in fact, present in some earlier versions of the virus, although it was in a somewhat-less-advanced form.

"That capability was in previous versions. I think what set off the red flag this time is the prevalence of this version and the potential for what could happen," said Ian Hameroff, eTrust security strategist at Computer Associates International Inc., in Islandia, N.Y.

SoBig.F instructed infected machines to connect to one of 20 IP addresses that were hidden in the viruss code. The PCs were then supposed to download and execute an unknown file. Security experts feared that the file could be a Trojan or some tool for launching a broader attack.

However, authorities were able to locate and shut down the vast majority of the 20 machines, and the expected onslaught of activity never materialized. The self-updating capability was first seen in SoBig.C, but until this latest version, none of the viruses had the list of IP addresses for infected machines to contact.

Further, some experts have said they believe that the SoBig viruses are being written, released and subsequently improved upon by professionals who have some larger goal in mind than simply flooding in-boxes with useless e-mail.

The fact that some portion of the self-updating feature was in previous versions of the virus would appear to bolster the argument for this trial-and-error scenario. But some in the anti-virus community dont buy it.

"We havent seen any evidence of this being used as a mechanism for sending commercial spam," said Chris Wraight, technology consultant at Sophos Inc., an enterprise anti-virus company based in Lynnfield, Mass. "Its definitely weird that a new one is released so often. Its almost like beta testing."

The saga of the Blaster worm followed much the same script but with a compressed time frame. The original Blaster hit the Internet Aug. 11 and was soon spreading furiously. Within a week or so, at least two variants of the worm were on the loose, each with a slight modification. One of the versions went into Blaster-infected PCs and attempted to download and install the patch for the vulnerability that Blaster exploits.

The other variant, known as Blaster.B, or Teekid, was little different from the original, except that its alleged creator intended to use it to control previously compromised machines. Still, CAs Hameroff isnt inclined to give the crackers too much credit. "Certainly, the creators benefit from the fact that its almost an open-source community. Theres a lot of sharing. The black hats enjoy bragging and showing off their successes, so to speak. But I dont think its a coordinated effort. It just shows that as we build a better mousetrap, they build better mice."