Anti-virus researchers are sounding the alert for a massive, well-coordinated hacker attack using three different Trojans to hijack PCs and create botnets-for-hire.
The three-pronged attack is being described as "unprecedented" because of the way the Trojans communicate with each other to infect a machine, disable anti-virus software and leave a back door open for future malicious use.
"This is so slick, its scary," said Roger Thompson, director of malicious content research at Computer Associates International Inc. "It clearly points to a very well-organized group either replenishing existing botnets or creating new ones."
According to Thompson, the wave of attacks start with Win32.Glieder.AK, dubbed Glieder, a Trojan that downloads and executes arbitrary files from a long, hardcoded list of URLs.
Glieders job is to sneak past anti-virus protection before definition signatures could be created and "seed" the infected machine for future use. At least eight variants of Glieder were unleashed on one day, wreaking havoc across the Internet.
On Windows 2000 and Windows XP machines, Glieder.AK attempts to stop and disable the Internet Connection Firewall and the Security Center service, which was introduced with Windows XP Service Pack 2.
The Trojan then quickly attempts to connect to a list of URLs to download Win32.Fantibag.A (Fantibag) to spawn the second wave of attacks.
With Fantibag on the compromised machine, Thompson said the attackers can ensure that anti-virus and other protection software is shut off. Fantibag exploits networking features to block the infected machine from communicating with anti-virus vendors. The Trojan even blocks access to Microsofts Windows Update, meaning that victims cannot get help.
Once the shields are down, a third Trojan called Win32.Mitglieder.CT, or Mitglieder, puts the hijacked machine under the complete control of the attacker.
Once the three Trojans are installed, the infected computer becomes part of a botnet and can be used in spam runs, distributed denial-of-service attacks or to log keystrokes and steal sensitive personal information.
A botnet is a collection of compromised machines controlled remotely via IRC (Inter Relay Chat) channels.
According to CAs Thompson, the success of the three-pronged attack could signal the end of signature-based virus protection if Trojans immediately disable all means of protection.
"These guys have worked out that they bypass past signature scanners if they tweak their code and then release it quickly. The idea is to hit hard and spread fast, disarm victims and then exploit them," Thompson said in an interview with Ziff Davis Internet News.
He said he thinks the attack, which used virus code from the Bagle family, is the work of a very small group of organized criminals. "Theres no doubt in my mind we are dealing with organized crime. The target is to build a botnet or to add to existing ones. Once the botnets reach a certain mass, they are rented out for malicious use."
"Theres a black market for infected computers. The bigger your botnet, the more money you can make," Thompson said. He said researchers tracking underground hacker activity had seen a price tag of about 5 cents per infected machine.