Ubuntu Security Notice USN-1008-2
21st October, 2010
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 10.04 LTS
Updated virtinst for use with the new libvirt.
- virtinst - Programs to create and clone virtual machines
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.
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.
The problem can be corrected by updating your system to the following package version:
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.