According to Graham, for about $1,000 per month attackers could simply be renting the cloud-based resources required to sustain their 70 Gbps attacks. "I guess $1,000 is more than most individuals might want to pay, but it's not at the 'state sponsored' level," he said. "It's more at the level of some rich dude giving a credit card to his son telling him 'you and your friends, go have some fun.'"

What of the ideological basis of the attacks -- instead of financial gain -- which some experts have cited as evidence of state sponsorship? Regardless of whether that's true, Herberger said it means that more than one group of actors is likely now involved. "The attack is an ideological call to arms -- or cyber attack -- so it begs the question, 'were there no people who subscribed to the call, and who have conscripted themselves to the call, and actually participated in the call?'" he said. In other words, the success of the self-described Muslim hacktivists' attacks against U.S. banks has likely led to more people signing up to participate.

Is there any other potential evidence of Iranian government involvement? In November, social engineering specialist Jennifer Emick, who runs Asherah Research Group and was previously part of Backtrace Security, published an analysis of the supposed hackers involved in the attacks, based on a close reading of the social networking ties for the owner of the Hilf-ol-Fozoul blog, which has championed Operation Ababil.

"This is definitely an Iranian operation, without a doubt," said Emick. "Also, curiously, these [social networking] accounts do not appear to be hackers, and pro-Anonymous and pro hacking groups are notably absent from the genuine Facebook groups/accounts," which she read as evidence of the blog's owner and friends identifying strongly with the Iranian government.

In late November, however, the bank attackers issued a Pastebin post denying that they were sponsored by any state, and implying that the owner of the Hilf-ol-Fozoul blog is essentially just a fanboy. Furthermore, they said that the only official communications from the group have come from its Pastebin account.

Finally, what if Iran did launch the attacks; what might be done? According to Karen Greenberg, who directs the Center on National Security at Fordham Law School, "if hacking is deemed to be the work of state governments, in this case, Iran, then the crime rises to the level of international diplomacy." In other words, the State Department will sort it out. Until then, Greenberg cautioned against rushing to judgment, given the difficulty involved in tracing attacks back to their source. "Careful, skillful attribution is crucial and exceedingly difficult," she said via email.

What's required is non-repudiation, said Radware's Herberger, referring to the technical term in information security that means clearly documenting that someone did something. But with the bank attacks, he said, "it's a very technically difficult situation," and such evidence has yet to be publicly produced.

"Now if you're the U.S. government, maybe you're hearing chatter, or have other evidence that suggests this is a campaign organized by a nation state," he said. "But if so, we're not privy to that information."

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