Debian attacker may have used new exploit

An as-yet-unknown security exploit in Linux may have been responsible for a recent compromise of Debian.org's servers, according to a system administrator with the Debian operating system project.

Initial investigations of the security breach, which occurred on 19 November, indicate that the attacker was able to gain full control of Debian servers after logging on via unprivileged accounts, known as privilege escalation, according to James Troup, part of the team handling Debian's distribution.

"I believe that there was an as-yet-unknown local root exploit used to go from having local unprivileged access to having root," Troup wrote in an email to a Debian mailing list on Friday. "There is [I believe] an unknown local root exploit in the wild."

The exploit was carried out on Debian software running on Intel-based hardware, while a system using Sun hardware was not affected, leading some to guess that Sun software is not affected by the possible exploit.

The attacker initially logged onto an unprivileged account on the server klecker.debian.org, using a stolen password, then attained full administrative -- or "root" -- access, and installed a hacker toolkit called Suckit, according to Troup. A similar technique was used on several other servers.

The compromised servers were all running recent versions of the Linux core, and had almost all security updates installed, lending weight to the argument that the attacker used an exploit that hasn't yet been discovered and patched.

Administrators detected the intrusion because of a glitch in the Suckit code, which caused anomalies in the kernels of compromised machines, Troup said.

Because investigators don't know exactly how the attacker was able to gain control of the Debian servers, the Debian project was forced to lock all user accounts, and is still unable to unlock the accounts. "Since we... knew we had compromised accounts and sniffers on our hands we had to assume that that an unknown number of accounts were now compromised," Troup wrote.

He said administrators are currently restoring the Debian machines one by one, while looking to determine how the attacker escalated account privileges.

"Obviously we're looking at hardening our boxes and tightening up our procedures to try and stop this from happening again," Troup wrote.

Information on securing Debian machines in the wake of the compromise can be found on developer site wiggy.net, Troup said.