USN-670-1: VMBuilder vulnerability

13 November 2008

vm-builder vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 8.10
  • Ubuntu 8.04 LTS
  • Ubuntu 7.10
  • Ubuntu 6.06 LTS

Software Description

  • shadow
  • vm-builder


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.

Update instructions

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

Ubuntu 8.10
passwd - 1:4.1.1-1ubuntu1.1
python-vm-builder - 0.9-0ubuntu3.1
Ubuntu 8.04 LTS
passwd - 1:
Ubuntu 7.10
passwd - 1:
Ubuntu 6.06 LTS
passwd - 1:4.0.13-7ubuntu3.3

To update your system, please follow these instructions:

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