A U.S. Federal Bureau of Investigation spokesman said Wednesday the agency is working with the Secret Service to determine the "scope" of reported cyberattacks against several financial institutions.
Bloomberg reported on Wednesday that Russian hackers struck JPMorgan Chase and another bank earlier this month. A subsequent report in the New York Times said the attacks hit JPMorgan Chase and four other U.S. financial institutions.
The Times reported that "gigabytes" of information were stolen, including customer account information.
A JPMorgan Chase spokeswoman did not confirm the attacks, saying that "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."
Representatives for Wells Fargo, Bank of America and Citigroup -- also frequent targets for hackers -- could not be immediately reached for comment.
FBI spokesman Paul Bresson said via email that combating cyber threats is a top priority for the government, and the agency constantly works with U.S. companies to fight attacks.
Media reports speculated the attacks could be in retaliation due to sanctions against Russia for its actions in Ukraine, but the motives remain unclear.
Quoting an anonymous source, Bloomberg wrote that one of the attacks was executed via a zero-day vulnerability in one of the bank's websites. A zero-day flaw is one that attackers are exploiting but for which there is no fix.
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