The attacked banks that we know about from news reports include Bank of America, JPMorgan Chase, Wells Fargo, U.S. Bank and PNC Bank. What happens in these incidents is that massive amounts of traffic including malware are channeled to the websites and non-consumer web-servers until they are overwhelmed and are forced to shut down until the attack is repelled, or it passes.
How serious is it all? "No bullets have been fired, but rest assured, this is truly a terrorist strike at the United States", says a security expert, Paul Rothman, writing ["Cyber Terror Rages In The Banking Sector"] on the Security Infowatch website yesterday. A CNN article ["Major banks hit with biggest cyberattacks in history"] puts into perspective this way:
"The volume of traffic sent to these sites is frankly unprecedented," said Dmitri Alperovitch, co-founder of CrowdStrike, a security firm that has been investigating the attacks. "It's 10 to 20 times the volume that we normally see, and twice the previous record for a denial of service attack." [More]
We don't know (of course) but Alperovitch of CrowdStrike says the Hamas group has credibility: they announced the attack ahead of time [source], and listed the banks that were going to be hit next. He says that technologically what they was "not that sophisticated -- it just took significant planning". On the other side of the ledger, Hamas also claimed they would attack the New York Stock Exchange but it appears trading has continued there without interruption [source].
Are we ever ready for terrorism?