The FBI says it's working with the Secret Service to investigate reports that Russian hackers breached security at JPMorgan Chase and other financial institutions, stealing customers' account information in possible retaliation for U.S. government sanctions on Moscow.
"We are working with the United States Secret Service to determine the scope of recently reported cyberattacks against several American financial institutions," FBI spokesman Joshua Campbell said in a statement late Wednesday.
Bloomberg News first reported that as Russian troops massed on the Ukrainian border and the West tightened sanctions, Russian hackers allegedly broke into the banks' servers and grabbed gigabytes of sensitive data. It said that information included checking and savings account information.
Security experts quoted in the Bloomberg report said the attack appeared to be "far beyond the capability of ordinary criminal hackers."
The New York Times, citing people familiar with the investigation, reported late Wednesday that at least four other U.S. banks were infiltrated in coordinated attacks this month.
While JPMorgan did not directly confirm the incident, spokesman Brian Marchiony said in a statement: "Companies of our size unfortunately experience cyberattacks nearly every day. We have multiple layers of defense to counteract any threats and constantly monitor fraud levels."
Earlier this month, U.S. officials said Russian hackers had stolen a record 1.2 billion username and password combinations.