A new "sophisticated" attack that uses three pieces of malware to turn PCs into zombies that can be sold to criminal groups has appeared on the Internet this week, security vendor Computer Associates International (CA) said Thursday.
A version of the Bagle worm downloader that CA has dubbed Glieder is serving as a "beachhead" to install more serious malware on computers, CA said. Showing a new level of coordination between Glieder and other attacks, infected computers can have their antivirus and firewall software disabled and can be turned into remotely controlled zombies used to mount large cyberattacks, CA said.
"This is so coordinated that it's remarkably sophisticated," said Roger Thompson, CA's director of malicious content research.
CA noted eight variants of Glieder released one after the other on Wednesday, "dazzling the Internet with their speed and deployment to maximize the number of compromised victims," the company said. "The whole point is to get to as many victims as fast as possible with a lightweight piece of malware."
The Glieder downloader then directs the infected computer to a Web site to download the Fantibag Trojan, which targets computers' networking features to prevent their systems from communicating with antivirus vendor update tools and with Microsoft's update Web site. Then, the infected computer will download the Mitglieder Trojan, which disables firewalls and antivirus software and opens a back door, allowing the computer to be controlled remotely by the hackers.
"It turns computers into zombies," Thompson said of the attack. "It's all about these guys building their botnet. It's all about making money."
As soon as antivirus vendors update their programs to detect the latest version of Glieder, the attackers would modify the downloader program, resulting in an arms race, Thompson added. The use of three separate pieces of malware to attack a computer shows a new level of coordination, he said. A black market for compromised computers drives these types of zombie attacks, with criminals paying for groups of machines to use as spam relays or as sources of personal information used in identity-theft schemes.
Other Internet security experts were less impressed with the Glieder attacks. While the pairing of Glieder with Fantibag may be new, Glieder and older Bagle variants are designed to work as downloader programs that can secretly install software on compromised machines, said Ken Dunham, director of malicious code at iDefense, another cybersecurity vendor.
CA warned that the new attacks may be the work of criminals. "There's plenty of evidence to suggest that all these things are being done by organizations," Thompson said.
Like CA, Jimmy Kuo, a research fellow with the McAfee Anti-Virus Emergency Response Team, sees a black market for zombie machines. McAfee has found evidence of criminals paying hackers to send out rounds of zombie malware attacks, he said. "The payments range form the high hundreds of dollars to the low thousands of dollars," he said.
Kuo didn't notice the same kind of attack that CA reported this week, but he noted that downloader attacks are becoming common, and that nearly all such attacks are associated with criminal activity. In some cases, zombie machines are used to attack corporate networks by flooding them with e-mail, he said. "It's probably to the point where somewhere in the high 90 percent of all malware is associated with a money-making scheme," he said.
Dunham suggested that small-time criminals or loosely organized hacking groups, not organized crime syndicates, start most such attacks.
"It is increasingly sophisticated, but not by much," Dunham said of the downloader-type attacks. "I'm not very impressed with them. I've seen much more sophisticated attacks with spyware this year than any of the downloader attacks."
Thompson and Dunham advised computer users to avoid opening any executable files they receive in e-mail. In most cases, security policies on corporate networks prohibit e-mail with executables from being delivered, but most PCs don't have the same protection, Thompson said.