Citigroup Says Cyber Attackers Gained Access to Customer Data

Citigroup Inc., the third-largest U.S. lender, said cyber attackers got into customer accounts last year as the threat of electronic intrusions increased.

The bank cited data breaches that gave outsiders access to account information or interrupted service, and attacks on systems run by clients that gave the intruders entrance to Citigroup’s systems so they could extract customer data, according to the bank’s annual report to securities regulators. Citigroup said it also suffered denial-of-service attacks, which typically involve outsiders causing a website to crash.