US banking company Wells Fargo is believed to have become the latest victim of a cyber-attack launched by a group pledging retaliation for the controversial Innocence of Muslims video that has triggered anger and violence across the Muslim world.
A group calling itself Izz ad-Din al-Qassam Cyber Fighters has claimed responsibility for the online attacks on US banks in protest against the online video. The attacks were launched last week under the name Operation Ababil, meaning "swarm", and have already affected banks including JP Morgan and Bank of America.
Wells Fargo acknowledged via Twitter that its website was having difficulties. The website Sitedown.co received hundreds of complaints from customers who were locked out of Wells Fargo's website on Wednesday.
Bank of America and JP Morgan were targeted on Tuesday, leading to widespread complaints from customers unable to access their accounts online. Sitedown received nearly a 1,000 complaints about outages at JP Morgan's site last week.
Dmitri Alperovitch, chief executive of CrowdStrike, a private security firm investigating the attacks, known as distributed denial of service or DDoS, said: "It's important to note that nobody's information has been compromised and no data has been stolen."
Alperovitch said the group claiming responsibility also launched attacks in early summer, long before the release of the video. "We believe claiming this has something to do with the video is a ruse," he said.
He said the attacks, while not sophisticated, were massive in scale and well co-ordinated. Some of the attacks have flooded the bank's websites with information at up to 100 gigabits a second; the usual DDoS attack is in the order of 5-10 gigabits a second.
Senator Joe Lieberman blamed Iran last week for the recent cyber-attacks. "I believe it was a response to increasingly strong economic sanctions the US and its allies have put on Iranian financial institutions. It is, if you will, a counterattack by Iran against American financial institutions," he told C-Span.
Alperovitch said he had not seen anything that would confirm or deny Lieberman's allegations.
• This article was amended on 27 September 2012 because it omitted the word "distributed" from the phrase "distributed denial of service".
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