Carter discloses Russian hack of Pentagon

SAN FRANCISCO -- Earlier this year, Russian hackers breached one of the Defense Department’s unclassified computer networks, Secretary Ashton Carter revealed April 23.

The Russian hackers "discovered an old vulnerability in one of our legacy networks that hadn't been patched," he told an audience at Stanford University. "While it's worrisome they achieved some [unauthorized] access to our unclassified network, we quickly identified the compromise, and had a team of incident responders hunting down the intruders within 24 hours."

Pentagon analysts studied the hackers' network activity and promptly evicted them from the network "in a way that minimized their chances of returning," Carter added.

The Pentagon boss disclosed the incident publicly for the first time in the name of transparency, and to add dramatic effect to the cyber strategy he was unveiling at Stanford. The strategy's tenets include accelerating cyber-related R&D at the Pentagon, conducting an assessment of the DOD cyber mission force's ability to deal with multiple threats, and fleshing out the department’s deterrence doctrine.

With the Russian hacking episode revealed, Carter turned to the unknown. "I still worry about what we don’t know because this was only one attack that we found," he said.