7.2 - USN-670-1

A security issue affects the following Ubuntu releases:

Ubuntu 6.06 LTS Ubuntu 7.10 Ubuntu 8.04 LTS Ubuntu 8.10

This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu.

The problem can be corrected by upgrading your system to the following package versions:

Ubuntu 6.06 LTS:
passwd 1:4.0.13-7ubuntu3.3

Ubuntu 7.10:
passwd 1:4.0.18.1-9ubuntu0.1

Ubuntu 8.04 LTS:
passwd 1:4.0.18.2-1ubuntu2.1

Ubuntu 8.10:
passwd 1:4.1.1-1ubuntu1.1
python-vm-builder 0.9-0ubuntu3.1

In general, a standard system upgrade is sufficient to effect the necessary changes.

Details follow:

Mathias Gug discovered that vm-builder improperly set the root password when creating virtual machines. An attacker could exploit this to gain root privileges to the virtual machine by using a predictable password.

This vulnerability only affects virtual machines created with vm-builder under Ubuntu 8.10, and does not affect native Ubuntu installations. An update was made to the shadow package to detect vulnerable systems and disable password authentication for the root account. Vulnerable virtual machines which an attacker has access to should be considered compromised, and appropriate actions taken to secure the machine.