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"These attacks are representative of the longest persistent cyber attack on an industry sector in history -- in fact, nearly every major commercial bank has been affected," said Carl Herberger, vice president of security solutions at Radware.
Another security vendor, Incapsula, recently analyzed DDoS attack code used by Izz ad-Din al-Qassam. The code came from the Web server of a U.K. customer. The server received instructions from a command-and-control server that timed the attacks to occur for periods from seven minutes to an hour. The precise timing made the attacks more effective.
"The botnet [command and control] was commanding it to work in 'shifts,' maximizing its efficiency and ordering it to renew the attack just as the target would start to recover," Incapsula said in a blog post.
The code was designed to multiply itself, so it could take full advantage of the server's capacity, Incapsula said. As a result, the traffic volume produced was much more than a compromised PC in a traditional botnet.
In a Jan. 1 post on Pastebin, Izz ad-Din al-Qassam vowed to continue the bank attacks, which it calls Operation Ababil. On Tuesday, the group said the attacks would continue until YouTube removed an anti-Islam video that mocked the Prophet Muhammad. The video, called the Innocence of Muslims, sparked violent demonstrations last year in many Middle Eastern countries.
Despite the group's demands, security experts and U.S. government officials believe the attacks are actually in retaliation for Western economic sanctions and for cyber attacks on Iranian computer systems. Over the last three years, three sophisticated viruses, Duqu, Flame and Stuxnet, have struck government systems. The Times reported last year that the U.S. and Israel were behind the 2010 Stuxnet attack that damaged centrifuges in Iranian nuclear facilities.
Iran has denied involvement in the bank attacks.
Read more about malware/cybercrime in CSOonline's Malware/Cybercrime section.