DDOS

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.

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.

Recently a DDoS attack hit various services provided by Amazon which left many users wanting to access its various web based services.