Banks have been warned to bolster their defences against hackers following unexplained outages on the Bank of America and JPMorgan Chase's websites.
The Financial Services Information Sharing and Analysis Center (FS-ISAC) upgraded its Cyber Threat Advisory status from Elevated to High on Thursday.
"Issues of concern include the recent credible intelligence regarding the potential for DDoS and other cyber attacks against financial institutions," read FS-ISAC's statement.
The two banks websites suffered outages after an unidentified person posted a statement on Pastebin threatening to attack Bank of America and the New York Stock Exchange.
The threat claimed the attacks would be the "first step" in an ongoing campaign against US companies.
The statement promised the attacks will continue until a controversial film, which prompted mass anti-American protests in the Middle East, is removed from the internet.
At the time of publishing neither JPMorgan or the Bank of America had responded to V3's request for comment.
FS-ISAC also cited the emergence of the recently discover zero-day vulnerability in Microsoft Internet Explorer as another key reason for the increased threat level.
"Additionally, Microsoft is aware of targeted attacks via active exploitation of a zero-day remote code execution vulnerability in Internet Explorer," read the warning.
"Members should maintain a heightened level of awareness, apply all appropriate updates and update AV and IDS/IPS signatures, and ensure constant diligence in monitoring and quick response to any malicious events."
The news follows on from widespread warnings within the security industry that hackers are developing their attack methods.
Most recently Trend Micro highlighted Eastern European hacker groups as a key threat facing financial institutions.
For more insight into some of the major security issues affecting businesses make sure you sign up to the V3 Security Summit taking place on Tuesday 25 September which includes high-level speakers such as Mimecast chief scientist Nathaniel Borenstein and cryptographer Bruce Schneier.
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