In a statement, Dow Jones says: "to the best of our knowledge, we have received no information from the authorities about any such alleged matter, and we are looking into whether there is any truth whatsoever to this report by a competitor news organization." Despite that strong denial (and shade thrown at Bloomberg's reporting), CNBC received confirmation from the FBI's New York office that it was indeed aware of the hack and investigating it.

For months, the FBI and SEC have been trying to determine exactly what sort of data was accessed and how the hackers could have profited from the breach. Some of Bloomberg's sources claimed that the hackers were able to view news stories not yet released for publication, some of which could have provided information and news about companies that hadn't been released to the public. And this isn't the first hack centered around finding insider info: earlier this year, Ukrainian hackers infiltrated servers from PR companies like PR Newswire and Businesswire for five years to access unreleased press releases from major corporations.

[Image credit: AP/Mary Altaffer]