The hack into the Pentagon's Joint Chiefs of Staff email network has “all the hallmarks of a state-sponsored attack,” a defense official told VOA.
The attack occurred around July 25, causing a shutdown that is still ongoing.
The Pentagon took the “most conservative” approach when responding to the intrusion, which was “to bring the network completely down in order to make the necessary fixes to it,” Pentagon spokesman Capt. Jeff Davis told reporters Friday.
U.S. media, including NBC and The Daily Beast, are reporting that hackers who penetrated the email network are based in Russia. The news outlets quote unnamed Pentagon officials.
However, a Pentagon official close to the situation told VOA Friday, “we don’t know who did it.”
The attack affected about 4,000 military and civilian personnel. NBC, quoting unnamed sources, said no classified information was seized or compromised.
The hack was quickly caught and resulted in little damage, according to Truman National Security Fellow Bob Stasio.
“The Obama administration since 2008 has really invested in cyber,” Stasio, a former cyber officer for the National Security Agency said. “It looks like the investments are paying off.”
He said Russia has a high ability to steal government secrets, but China is the larger overall threat to U.S. cyber security because it uses “national security resources to go after [the U.S.] economic sector.”
U.S. officials recently confirmed that about 21 million U.S. government employees, contractors and others had personal information compromised in two other cyber attacks suspected to have originated in China.
Doug Bernard contriubuted to this report from Washington.