The FBI disclosed that it has already mitigated a cybersecurity incident on its network, with officials already investigating the extent and impact of the detected malicious cyber activity, following an earlier report from CNN that detailed a hack into the agency's New York Field Office computer system, BleepingComputer reports. "This is an isolated incident that has been contained. As this is an ongoing investigation the FBI does not have further comment to provide at this time," said the FBI. The reported hack comes more than a year after the FBI had its email servers compromised to deploy spam emails purporting as warnings of a "sophisticated chain attack." At least 100,000 mailboxes may have been targeted by the malicious messages, which have ben sent from [email protected], which is being used by agency's Law Enforcement Enterprise Portal, but SpamHaus noted that the malicious campaign may have had a significantly larger impact.