USN-1008-4: libvirt regression

8 November 2010

libvirt regression

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

  • Ubuntu 10.04 LTS

Summary

This update restores ‘host_device’ support for domain XML on Ubuntu 10.04 LTS.

Software Description

  • libvirt - the programs for the libvirt library

Details

USN-1008-1 fixed vulnerabilities in libvirt. The upstream fixes for CVE-2010-2238 changed the behavior of libvirt such that the domain XML could not specify ‘host_device’ as the qemu sub-type. While libvirt 0.8.3 and later will longer support specifying this sub-type, this update restores the old behavior on Ubuntu 10.04 LTS.

We apologize for the inconvenience.

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
libvirt0 - 0.7.5-5ubuntu27.7

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