But there was something disturbingly different about the wave of online attacks on American banks in recent weeks. Security researchers say that instead of exploiting individual computers,
the attackers engineered networks of computers in data centers, transforming the online equivalent of a few yapping Chihuahuas into a pack of fire-breathing Godzillas.
The skill required to carry out attacks on this scale has convinced United States government officials and security researchers that they are the work of Iran, most likely in retaliation for economic sanctions and online attacks by the United States.
“There is no doubt within the U.S. government that Iran is behind these attacks,” said James A. Lewis, a former official in the State and Commerce Departments and a computer security expert at the Center for Strategic and International Studies in Washington.
Mr. Lewis said the amount of traffic flooding American banking sites was “multiple times” the amount that Russia directed at Estonia in a monthlong online assault in 2007 that nearly crippled the Baltic nation.
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The scale, the scope and the effectiveness of these attacks have been unprecedented,” said Carl Herberger, vice president of security solutions at Radware, a security firm that has been investigating the attacks on behalf of banks and cloud service providers. “
There have never been this many financial institutions under this much duress.”