A network intrusion at the Pentagon nine months ago resulted in the theft of an "amazing amount of data" that continues to pose a threat to national security, the CIO of the Defense Department said earlier this week.

"This was a very bad day," Dennis Clem, who is also CIO of the Office of the Secretary of Defense, said during a panel discussion at the Information Processing Interagency Conference. "We don't know when they'll use the information they stole, [which was] an amazing amount." The pilfered data included processes and procedures that will be valuable to US enemies, he said, according to an article by Government Executive.

Over the course of two months leading up to the attack, malicious code infiltrated several systems belonging to the Pentagon's network and culminated in an exploit of a known Microsoft Windows vulnerability, Clem said. That allowed attackers to send spoofed emails that appeared to come from Pentagon personnel in Clem's division.

Somehow, the emails managed to steal login credentials for the network, according to this article from Federal Computer Week. Network forensics show the hackers were able to access sensitive information, which they encrypted as they transmitted it back to their sites.

Clem's statements are just a tad more telling than those of US Secretary of Defense Robert Gates when first disclosing the June 2007 breach to reporters. "There will be some administrative disruptions and personal inconveniences," he said at the time. "It will come as no surprise that we aggressively monitor intrusions and have appropriate procedures to address events of this kind."

Clem didn't identify the attackers, but according to some published reports, government investigators believe the the breach originated in China. It took three weeks and $4m to clean up the mess.

Clem said the Pentagon gets 70,000 malicious entry attempts per day, ranging from relatively innocuous probes to more nefarious attacks. Outside hackers can pinpoint new servers or software within minutes of them being deployed and intrusions quickly follow. ®