Debian Server restored after Compromise

July 13th, 2006

One core Debian server has been reinstalled after a compromise and services have been restored. On July 12th the host gluck.debian.org was compromised using a local root vulnerability in the Linux kernel. The intruder had access to the server using a compromised developer account.

The services affected and temporarily taken down are: cvs, ddtp, lintian, people, popcon, planet, ports and release.

Details

At least one developer account was compromised a while ago and has been used by an attacker to gain access to the Debian server. A recently discovered local root vulnerability in the Linux kernel has then been used to gain root access to the machine.

At 02:43 UTC on July 12th suspicious mails were received and alarmed the Debian admins. The following investigation turned out that a developer account was compromised and that a local kernel vulnerability had been exploited to gain root access.

At 04:30 UTC on July 12th gluck has been taken offline and booted off trusted media. Other Debian servers have been locked down for further investigation whether they were compromised as well. They will be upgraded to a corrected kernel before they will be unlocked.

Due to the short window between exploiting the kernel and Debian admins noticing, the attacker hadn't had time/inclination to cause much damage. The only obviously compromised binary was /bin/ping.

The compromised account did not have access to any of the restricted Debian hosts. Hence, neither the regular nor the security archive had a chance to be compromised.

An investigation of developer passwords revealed a number of weak passwords whose accounts have been locked in response.

The machine status is here.

Kernel vulnerability

The kernel vulnerability that has been used for this compromise is referenced as CVE-2006-2451. It only exists in the Linux kernel 2.6.13 up to versions before 2.6.17.4, and 2.6.16 before 2.6.16.24. The bug allows a local user to gain root privileges via the PR_SET_DUMPABLE argument of the prctl function and a program that causes a core dump file to be created in a directory for which the user does not have permissions.

The current stable release, Debian GNU/Linux 3.1 alias 'sarge', contains Linux 2.6.8 and is thus not affected by this problem. The compromised server ran Linux 2.6.16.18.

If you run Linux 2.6.13 up to versions before 2.6.17.4, or Linux 2.6.16 up to versions before 2.6.16.24, please update your kernel immediately.

About Debian

Debian GNU/Linux is a free operating system, developed by more than a thousand volunteers from all over the world who collaborate via the Internet. Debian's dedication to Free Software, its non-profit nature, and its open development model make it unique among GNU/Linux distributions.

The Debian project's key strengths are its volunteer base, its dedication to the Debian Social Contract, and its commitment to provide the best operating system possible.

Contact Information

For further information, please visit the Debian web pages at http://www.debian.org/ or send mail to <press@debian.org>.