botnet

The Kraken botnet, believed by many to be the single biggest zombie network until it was dismantled last year, is staging a comeback that has claimed almost 320,000 PCs, a security researcher said.

Since April, this son-of-Kraken botnet has infected an estimated 318,058 machines - about half as big as the original Kraken was at its height in the middle of 2008, according to Paul Royal, a research scientist at the Georgia Tech Information Security Center.

Like its predecessor, the new botnet is a prodigious generator of spam, with a single machine with average bandwidth able to send more than 600,000 junk mails per day.

Security research teams monitoring the relative strength and activity of some of the world's largest botnets  are confined by legal restraints making them virtually powerless to stop them, according to a researcher at Kaspersky Lab Japan.

The botnet ecosystem is flourishing as a result of ineffective measures being undertaken by security researchers to get them shut down, Vitaly Kamluk, chief security expert at Kaspersky, told hundreds of incident response team members, Wednesday, at the Forum of Incident Response and Security Teams (FIRST) Conference 2010. Kamluk painted a bleak picture of the rising sophistication of botnets and the underground business environment that fuels them.

After an international take-down effort, a rogue ISP responsible for controlling large numbers of computers infected with data-stealing code is down for the moment, but it may be reconnecting with the Internet, according to security researchers.

Troyak, which is believed to be based in eastern Europe, was knocked offline earlier this month after other networks supplying its connectivity to the Internet stopped carrying its traffic due to complaints it was complicit in cybercrime.

Since then the network has fought a cat-and-mouse game with network providers in 12 countries and international law enforcement, according to Jart Armin, the pseudonymous editor of the Hostexploit.com Web site, which has been involved in the action.