White House down: Computer systems hacked by unconfirmed assailant

Hackers have apparently breached computer systems at the White House. White House authorities say they have taken steps to address suspicious activity detected on the network, which is part of the unclassified portion of US government networks.

There is as yet no details on the identity of the assailants, or why they might have infiltrated the White House network. An official said "activity of concern" was detected while identifying numerous possible cyber threats that the Executive Office of the President investigates daily.

Related: How 5 Chinese hackers stole American companies' most closely-guarded secrets

The measures put in place to identify the attackers and prevent further compromise have shut down the White House computer network temporarily, which has meant loss of connectivity for many White House employees.

The Washington Post reported that the intranet and VPN were both intermittently unavailable, but that email was largely unaffected apart from "minor delays".

"Certainly a variety of actors find our networks attractive targets and seek access to sensitive government information," a White House spokesperson told the press. "We are still assessing the activity of concern, and we are not in a position to provide any additional details at this time."

Tim Erlin of Tripwire told ITProPortal that "while the White House claims the attack hasn't caused any damage, the defensive measures put in place to respond have degraded service, which is a kind of damage and makes the attackers successful."

"Even though the affected systems are unclassified, it's unlikely that we'll receive a full account of the activity. The White House could take an important step forward in threat intelligence sharing by being more forthcoming with details of the attack in order to help others defend themselves as effectively as possible."

The US has in the past been the target of attacks originating from Iran, which compromised the Navy and Marine Corps Intranet (NMCI), the largest internal network in the world. It includes over 363,000 individual computers, and serves more than 700,000 Sailors, Marines and civilians in 620 locations across the continental US, Hawaii, and Japan.

The United States has also accused Iran of orchestrating a number of cyber-attacks against US energy companies, which officials have described as worrying. Back in May, the US indicted five members of an elite People's Liberation Army group codenamed Unit 61398, who were assigned to hack into some of the largest US companies and steal their secrets.

Read more: Iranian hackers gain access to US Navy network