Banking giant HSBC has confirmed its services were knocked offline following a distributed denial of service attack (DDoS).
In a statement the company said the attack did not affect customer data but did hit online services including internet banking, which was unavailable for a short period.
An updated statement added that all services were fully functional by 3am UK time on October 19.
"We are cooperating with the relevant authorities and will cooperate with other organisations that have been similarly affected by such criminal acts," the statement added. "We apologise for any inconvenience caused to our customers throughout the world."
A number of banks have been hit by cyber attacks recently. US banking giants J.P. Morgan Chase, Wells Fargo and Bank of America have all been hit by DDoS attacks that have disrupted services in some way. A group calling itself Mrt. Izz ad-Din al-Qassam Cyber Fighters claimed responsibilities for those attacks.
A statement posted online said the group was also behind the HSBC attack. The statement said the attack was part of Operation Ababil, which is thought to be backed by a group of Muslims targeting Western financial institutions. The group has said it will continue its attacks until a controversial film trailer is removed from the internet.
However another group has also claimed responsibility for the attack. FawkesSecurity said it carried out the attack but would not reveal why.
The group, which claims links with Anonymous, posted a statement on Pastebin: "As some of you may be aware HSBC bank suffered several DDoS attacks on the named sites in the past hours us.hsbc.com hsbc.co.uk hsbc.com hsbc.ca they were all brought down by #FawkesSecurity."
It also posted a video on YouTube.
DDoS attacks are a very effective way of disrupting a company’s online operations. Essentially a DDoS attack floods a website’s servers with so much traffic that it collapses, meaning no one can access it.
CBR has reached out to HSBC for comment but received no reply at the time of publication.