Mytob writers could be creating a superbug

IDG News Service - Virus writers responsible for the recent rash of Mytob worm variants could be working on creating a superworm, a security researcher warned today.
The HellBot group behind the Mytob worms writes programming instructions in its code that mirror the way developers work, said Sophos PLC security consultant Carole Theriault. "The only conclusion we can come up with is that they are working on a big superworm," she said.
Since its discovery in February, the Mytob mass-mailing worm has spawned dozens of variants, each just slightly different, according to researchers. However, each variant turns off an infected machine's security settings and blocks the user's access to security Web sites, Theriault said.
This makes it difficult to get help once a machine has been infected, and Trojan programs accompanying the worms could leave a back door open for a future attack, she said. One recent version included spyware and adware, which could be used to reap monetary benefits, according to Tokyo-based antivirus company Trend Micro Inc.
The Mytob authors have been "very busy," releasing multiple variants a day, McAfee Inc. noted. While the distribution of each variant is low, combined there is a lot of activity around them, researchers said.
More than 50% of the reported problems coming into Sophos during the last 24 hours have been about Mytob worms, Theriault said. Recent versions, discovered earlier in the week include Mytob.bi, which poses as a message from an IT administrator warning that the recipient's e-mail account is about to be suspended (see story). It scans the hard drive of an infected machine and sends copies of itself to e-mail addresses it finds in the Windows Address Book. It also prevents the machine from accessing several antivirus and security Web sites and can open a random port, allowing a hacker to gain remote access.
While antivirus companies would normally have to update their software to guard against each new variant, the Mytob family is so close that multiple variants can be caught using generic definitions of the worm, Theriault said. However, users are advised to keep their antivirus software up to date.