Suspected zombie kings who ran botnet of 100,000 PCs arrested, reports Sophos

October 10, 2005 Sophos Press Release

Zombie computers under the remote control of a hacker can launch a distributed denial-of-service attack. Image copyright (c) Sophos
The three men are said to have taken remote control of zombie computers.

Experts at SophosLabs™, Sophos's global network of virus, spyware and spam analysis center, have welcomed the news that authorities in the Netherlands have arrested three men suspected of running a zombie network of more than 100,000 computers.

The men, aged 19, 22 and 27, are accused of computer hacking, installing adware and spyware and using innocent people's compromised computers without their permission. Police confiscated computers, cash and a sports car during a search of the suspects' homes.

Prosecutors claim that the men ran a zombie network of 100,000 infected computers, one of the largest ever detected, which included computers around the world. Such zombie networks, also known as botnets, are often used to launch distributed denial of service attacks (DDOS) or to launch spam campaigns.

The suspects are alleged to have used the W32/Codbot worm (also known as Toxbot) to take remote control of the PCs of innocent computer users. A number of new versions of the Codbot worm have appeared since the start of 2005, as its authors changed its appearance in an attempt to avoid detection by anti-virus software. Some versions of the Codbot worm captured keypresses, in an attempt to commit identity fraud by stealing bank account information and credit card numbers.

Dutch authorities are investigating claims that the gang attempted to blackmail a North American organization. It is not unusual for criminal gangs to use zombie networks to extort money from online companies, forcing them to pay to prevent a DDOS attack against their websites.

"Zombie botnets are becoming an increasing security problem as they pump out spam campaigns, steal information, or launch attacks against corporate networks," said Graham Cluley, senior technology consultant for Sophos. "The Dutch authorities should be applauded for investigating this case, but with many other internet criminals in operation these arrests are unlikely to make a dramatic impact on the safety of the internet."

In August, an American teenager was sentenced to five years juvenile detention for launching DDOS attacks against online sportswear retailers.

Zombie computers - are your PCs under someone else's control?

Zombie computers can be used by criminal hackers to launch distributed denial-of-service attacks, spread spam messages or to steal confidential information. SophosLabs estimates that more than 60 percent of all spam today originates from zombie computers. In May, the Sober-Q Trojan horse and Sober-N worm worked in tandem to infect and hijack computers around the world, programming them to spew out German nationalistic spam during an election.

As spammers become more aggressive, collaborating with virus writers to create armies of zombie computers, legitimate organizations with hijacked computers are being identified as a source of spam. This not only harms the organization's reputation, but can also cause the company's email to be blocked by others.

Sophos ZombieAlert™ advises service subscribers when any computer on their network is found to have sent spam to Sophos's extensive global network of spam traps, and provides rapid notification to customers if their Internet Protocol (IP) addresses are listed in public Domain Name Server Block Lists (DNSBL). This information helps customers locate, disinfect, and protect these systems from future attacks.

Sophos continues to recommend that computer users ensure their anti-virus software is up-to-date, and that companies protect themselves with a consolidated solution which can defend them from the threats of spyware, spam and viruses.