Though U.S. officials blamed Iran for an ongoing stream of distributed denial of service attacks (DDoS) against major U.S. banks, security experts say there's not enough evidence yet to assign blame.
The security experts say that the attacks over the past few months appear to be very well planned and that the attackers have much knowledge of the weak spots in U.S. financial services networks, which could make them state sponsored.
Meanwhile, the ongoing attacks have reportedly prompted some banks to seek the help of the National Security Agency (NSA).
The Washington Post on Friday quoted an unnamed bank official as saying that banks are seeking NSA help due to a growing sophistication of DDoS attacks against them.
Earlier this week, the New York Times quoted a former official in the U.S State and Commerce Department as saying that there is "no doubt" within the U.S. government that Iran is behind the attacks.
A group calling itself "Izz ad-Din al-Qassam Cyber Fighters" has claimed responsibility for a series of DDoS attacks against several large U.S. banks including Wells Fargo, JP Morgan Chase, Bank of America and U.S. Bancorp.
The group claims to be based in Iran and says the attacks are in protest of YouTube's refusal to take down a trailer of the controversial anti-Islam movie that roiled much of the Middle East last year.
The DDoS attacks began last September and have shown no signs of abating.
If anything, the attacks have become more sophisticated and disruptive, said Scott Hammack, chief executive officer at Prolexic Technologies, a security firm that has been helping some of the largest U.S. banks fend off the attacks.
Unlike past DDoS attacks, the ongoing attacks are much more high-bandwidth and more frequent, Hammack said. For instance, Prolexic recently observed high-bandwidth attacks against two separate banks that were launched at the same time.
One of the attacks generated 75GBps of DDoS traffic while the other generated 45GBps. Such high-bandwidth attacks, which used to occur once or twice a year, have become almost routine, he said.
Unlike past DDoS attacks, in which attackers commanded hundreds of thousands of infected PCs to send streams of useless traffic to targeted systems, the latest ones involve thousands of comprised servers capable of generating far greater DDoS traffic, he said.
Whoever is behind the attacks also appears to be using so-called "push technology" to control the infected servers in real-time he said.
The technology allows attackers to turn on and turn off DDoS attacks and redirect DDoS streams at will, Hammack said. "They have a very good knowledge of what infrastructure to go after, particularly weak spots in the infrastructure," he said.
Defending against the attacks has been challenging because the servers used to launch them "are being told what to do in real-time," he said. However, the line of attack also "leaves the attackers completely exposed," which is how the U.S. government appears to know who is behind the attacks, he added.
"The attackers have been very brazen. This is being done by someone who doesn't really care about their identify being tracked," Hammack said.
He declined to speculate on the identity fo the attackers.
Retired Rear Admiral Mike Brown, vice president of RSA's federal business group, said there is currently no evidence that the attacks are state sponsored.
"But that can't be counted out of the realm of possibility given the pressure Iran is under from the U.S. and the international community," Brown said. "At the very least, Izz ad-Din al-Qassam appears to be a hacktivist group that is motivated by a nationalist agenda."
He also wouldn't speculate on the identity of the hackers.
Generally, nation states with a serious interest in cyber espionage and cyberwarfare usually employ substantial resources to develop custom malware and exploits for such attacks, he said.
Gartner analyst Avivah Litan noted that U.S. banking regulators such as the Office of the Comptroller of Currency (OCC) have pointed to multiple groups as potential attackers.
"Some are politically motivated and others are financially motivated," Litan said. "Most important, the DDoS attacks have in fact led to or been associated with fraud and customer account takeover," she said.
Regardless of who is behind the attacks, banks need to take them seriously, Litan said.
"They must revisit their network configurations and re-architect them in order to minimize the damage," she said. "For example, they should distribute and decentralize their DNS and Web application servers as much as possible, and set various parameters to deflect the damage that a DDoS attack can do."
The banks must also strengthen backup processes and organizational support to deal with the fallout from such attacks, Litan said. "Banks must deploy layered security and fraud prevention, as outlined in FFIEC guidance to mitigate financial damage from these attacks," she added.
Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan, or subscribe to Jaikumar's RSS feed . His e-mail address is firstname.lastname@example.org.