TD Bank says it was the victim of a targeted denial-of-service cyber attack that knocked its website and mobile banking app temporarily offline Thursday.
The bank says most services were restored within hours and the security breach did not compromise clients’ accounts or personal data.
Spokeswoman Barbara Timmins added that ATMs, the Easy Line telephone banking service, Internet brokerage WebBroker and branch functions were not impacted.
She did not comment on who may have been behind the denial-of-service attack, where hackers flood a target with a wave of requests that cause the target’s computer servers to crash under the load.
The attacks often use thousands of individual computers to forward the request, with the TD attack part of a wider phenomenon that has seen financial institutions targeted, often in the U.S. and increasingly involving mobile applications.
In September, for example, a group called Izz ad-Din al-Qassam Cyber Fighters claimed responsibility for a series of attacks on the websites of institutions including Bank of America, Citigroup, U.S. Bank and Wells Fargo.
The group said the banks were targeted in retaliation for what it called their online publication of an anti-Islam video.
Jeff Brueggeman, vice president, global public policy and deputy chief privacy officer at U.S.-based wireless network operator AT&T, said the increasing frequency and intensity of state-sponsored and other cyber attacks raises costs for all stakeholders, including consumers.
A participant in a forum called Cyber Dialogue held in Toronto this week, he added that attacks on mobile services could be the next wave of cyber warfare.