The pyGrub boot loader in Xen 3.0.3, 3.3.0, and Xen-3.3.1 does not support the password option in grub.conf for para-virtualized guests, which allows attackers with access to the para-virtualized guest console to boot the guest or modify the guest's kernel boot parameters without providing the expected password.

From Red Hat Security Advisory 2009:1472 :

Updated xen packages that fix a security issue and multiple bugs are now available for Red Hat Enterprise Linux 5.

This update has been rated as having moderate security impact by the Red Hat Security Response Team.

Xen is an open source virtualization framework. Virtualization allows users to run guest operating systems in virtual machines on top of a host operating system.

The pyGrub boot loader did not honor the 'password' option in the grub.conf file for para-virtualized guests. Users with access to a guest's console could use this flaw to bypass intended access restrictions and boot the guest with arbitrary kernel boot options, allowing them to get root privileges in the guest's operating system.
With this update, pyGrub correctly honors the 'password' option in grub.conf for para-virtualized guests. (CVE-2009-3525)

This update also fixes the following bugs :

* rebooting para-virtualized guests sometimes caused those guests to crash due to a race condition in the xend node control daemon. This update fixes this race condition so that rebooting guests no longer potentially causes them to crash and fail to reboot. (BZ#525141)

* due to a race condition in the xend daemon, a guest could disappear from the list of running guests following a reboot, even though the guest rebooted successfully and was running. This update fixes this race condition so that guests always reappear in the guest list following a reboot. (BZ#525143)

* attempting to use PCI pass-through to para-virtualized guests on certain kernels failed with a 'Function not implemented' error message. As a result, users requiring PCI pass-through on para-virtualized guests were not able to update the xen packages without also updating the kernel and thus requiring a reboot. These updated packages enable PCI pass-through for para-virtualized guests so that users do not need to upgrade the kernel in order to take advantage of PCI pass-through functionality. (BZ#525149)

All Xen users should upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the xend service must be restarted for this update to take effect.

CVE-2009-3525 Xen: PyGrub missing support for password configuration command

The pyGrub boot loader did not honor the 'password' option in the grub.conf file for para-virtualized guests. Users with access to a guest's console could use this flaw to bypass intended access restrictions and boot the guest with arbitrary kernel boot options, allowing them to get root privileges in the guest's operating system.
With this update, pyGrub correctly honors the 'password' option in grub.conf for para-virtualized guests. (CVE-2009-3525)

This update also fixes the following bugs :

  - rebooting para-virtualized guests sometimes caused those     guests to crash due to a race condition in the xend node     control daemon. This update fixes this race condition so     that rebooting guests no longer potentially causes them     to crash and fail to reboot. (BZ#525141)

  - due to a race condition in the xend daemon, a guest     could disappear from the list of running guests     following a reboot, even though the guest rebooted     successfully and was running. This update fixes this     race condition so that guests always reappear in the     guest list following a reboot. (BZ#525143)

  - attempting to use PCI pass-through to para-virtualized     guests on certain kernels failed with a 'Function not     implemented' error message. As a result, users requiring     PCI pass-through on para-virtualized guests were not     able to update the xen packages without also updating     the kernel and thus requiring a reboot. These updated     packages enable PCI pass-through for para-virtualized     guests so that users do not need to upgrade the kernel     in order to take advantage of PCI pass-through     functionality. (BZ#525149)

After installing the updatedpackages, the xend service must be restarted for this update to take effect.

Collective Xen/201004 Update, containing fixes for the following issues :

  - pygrub, reiserfs: Fix on-disk structure definition     bnc#537370 - Xen on SLES 11 does not boot - endless loop     in ATA detection bnc#561912 - xend leaks memory     bnc#564750 - Keyboard Caps Lock key works abnormal under     SLES11 xen guest OS. bnc#548443 - keymap setting not     preserved bnc#555152 - 'NAME' column in xentop (SLES11)     output limited to 10 characters unlike SLES10 bnc#553631
    - L3: diskpart will not run on windows 2008 bnc#548852 -     DL585G2 - plug-in PCI cards fail in IO-APIC mode     bnc#529195 - xend: disallow ! as a sxp separator     bnc#550397 - xend: bootable flag of VBD not always of     type int bnc#545470 - Xen vifname parameter is ignored     when using type=ioemu in guest configuration file     bnc#541945 - xm create -x command does not work in SLES     10 SP2 or SLES 11 bnc#542525 - xen pygrub vulnerability     (CVE-2009-3525) bnc#481592 and fate#306125 - Virtual     machines are not able to boot from CD to allow upgrade     to OES2SP1 (sle10 bug) bnc#553633 - Update breaks menu     access keys in virt-viewer and still misses some key     sequences. (sle10 bug) fate#306720: xen: virt-manager     cdrom handling. bnc#547590 - L3: virt-manager is unable     of displaying VNC console on remote hosts bnc#572691 -     libvird segfaults when trying to create a kvm guest     bnc#573748 - L3: Virsh gives error Device 51712 not     connected after updating libvirt modules bnc#548438 -     libcmpiutil / libvirt-cim does not properly handle CIM_     prefixed. (bnc#576832)

  - Xen doesn't work get an eror when starting the install     processes or starting a pervious installed DomU.
    (bnc#513921)

  - Cannot set MAC address for PV guest in vm-install.
    (bnc#526855)

Collective Xen 2010/04 Update, containing fixes for the following issues :

bnc#576832 - pygrub, reiserfs: Fix on-disk structure definition bnc#537370 - Xen on SLES 11 does not boot - endless loop in ATA detection bnc#561912 - xend leaks memory bnc#564750 - Keyboard Caps Lock key works abnormal under SLES11 xen guest OS. bnc#548443 - keymap setting not preserved bnc#555152 - 'NAME' column in xentop (SLES11) output limited to 10 characters unlike SLES10 bnc#553631 - L3:
diskpart will not run on windows 2008 bnc#548852 - DL585G2 - plug-in PCI cards fail in IO-APIC mode bnc#529195

  - xend: disallow ! as a sxp separator bnc#550397 - xend:
    bootable flag of VBD not always of type int bnc#545470 -     Xen vifname parameter is ignored when using type=ioemu     in guest configuration file bnc#541945 - xm create -x     command does not work in SLES 10 SP2 or SLES 11     bnc#542525 - VUL-1: xen pygrub vulnerability bnc#481592     and fate#306125 - Virtual machines are not able to boot     from CD to allow upgrade to OES2SP1 (sle10 bug)     bnc#553633 - Update breaks menu access keys in     virt-viewer and still misses some key sequences. (sle10     bug) fate#306720: xen: virt-manager cdrom handling.
    bnc#547590 - L3: virt-manager is unable of displaying     VNC console on remote hosts bnc#572691 - libvird     segfaults when trying to create a kvm guest bnc#573748 -     L3: Virsh gives error Device 51712 not connected after     updating libvirt modules bnc#548438 - libcmpiutil /     libvirt-cim does not properly handle CIM_ prefixed     bnc#513921 - Xen doesn't work get an eror when starting     the install processes or starting a pervious installed     DomU bnc#526855 - Cannot set MAC address for PV guest in     vm-install

Updated xen packages that fix a security issue and multiple bugs are now available for Red Hat Enterprise Linux 5.

This update has been rated as having moderate security impact by the Red Hat Security Response Team.

Xen is an open source virtualization framework. Virtualization allows users to run guest operating systems in virtual machines on top of a host operating system.

The pyGrub boot loader did not honor the 'password' option in the grub.conf file for para-virtualized guests. Users with access to a guest's console could use this flaw to bypass intended access restrictions and boot the guest with arbitrary kernel boot options, allowing them to get root privileges in the guest's operating system.
With this update, pyGrub correctly honors the 'password' option in grub.conf for para-virtualized guests. (CVE-2009-3525)

This update also fixes the following bugs :

* rebooting para-virtualized guests sometimes caused those guests to crash due to a race condition in the xend node control daemon. This update fixes this race condition so that rebooting guests no longer potentially causes them to crash and fail to reboot. (BZ#525141)

* due to a race condition in the xend daemon, a guest could disappear from the list of running guests following a reboot, even though the guest rebooted successfully and was running. This update fixes this race condition so that guests always reappear in the guest list following a reboot. (BZ#525143)

* attempting to use PCI pass-through to para-virtualized guests on certain kernels failed with a 'Function not implemented' error message. As a result, users requiring PCI pass-through on para-virtualized guests were not able to update the xen packages without also updating the kernel and thus requiring a reboot. These updated packages enable PCI pass-through for para-virtualized guests so that users do not need to upgrade the kernel in order to take advantage of PCI pass-through functionality. (BZ#525149)

All Xen users should upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the xend service must be restarted for this update to take effect.

The remote Redhat Enterprise Linux 5 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2009:1472 advisory.

  - Xen: PyGrub missing support for password configuration command (CVE-2009-3525)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
67935	Oracle Linux 5 : xen (ELSA-2009-1472)	Nessus	Oracle Linux Local Security Checks	high
60674	Scientific Linux Security Update : xen on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	high
50967	SuSE 11 Security Update : Xen (SAT Patch Number 2230)	Nessus	SuSE Local Security Checks	high
50966	SuSE 11 Security Update : Xen (SAT Patch Number 2230)	Nessus	SuSE Local Security Checks	high
46729	openSUSE Security Update : xen-201004 (openSUSE-SU-2010:0293-1)	Nessus	SuSE Local Security Checks	high
43799	CentOS 5 : xen (CESA-2009:1472)	Nessus	CentOS Local Security Checks	high
41963	RHEL 5 : xen (RHSA-2009:1472)	Nessus	Red Hat Local Security Checks	critical

Detections

Analytics

CVE-2009-3525

high

Tenable Plugins

high

high

high

high

high

high

critical