USN-1008-2: Virtinst update

21 October 2010

virtinst update

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

  • Ubuntu 10.04 LTS

Summary

Updated virtinst for use with the new libvirt.

Software Description

  • virtinst - Programs to create and clone virtual machines

Details

Libvirt in Ubuntu 10.04 LTS now no longer probes qemu disks for the image format and defaults to ‘raw’ when the format is not specified in the XML. This change in behavior breaks virt-install –import because virtinst in Ubuntu 10.04 LTS did not allow for specifying a disk format and does not specify a format in the XML. This update adds the ‘format=’ option when specifying a disk. For example, to import an existing VM which uses a qcow2 disk format, use somthing like the following:

virt-install –connect=qemu:///session –name test-import –ram=256
–disk path=<path to qcow2 image>,format=qcow2 –import

For more information, see man 1 virt-install.

Original advisory details:

It was discovered that libvirt would probe disk backing stores without consulting the defined format for the disk. A privileged attacker in the guest could exploit this to read arbitrary files on the host. This issue only affected Ubuntu 10.04 LTS. By default, guests are confined by an AppArmor profile which provided partial protection against this flaw. (CVE-2010-2237, CVE-2010-2238)

It was discovered that libvirt would create new VMs without setting a backing store format. A privileged attacker in the guest could exploit this to read arbitrary files on the host. This issue did not affect Ubuntu 8.04 LTS. In Ubuntu 9.10 and later guests are confined by an AppArmor profile which provided partial protection against this flaw. (CVE-2010-2239)

Jeremy Nickurak discovered that libvirt created iptables rules with too lenient mappings of source ports. A privileged attacker in the guest could bypass intended restrictions to access privileged resources on the host. (CVE-2010-2242)

Update instructions

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

Ubuntu 10.04 LTS
virtinst - 0.500.1-2ubuntu6.1

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

In general, a standard system update will make all the necessary changes.

References