Tavis Ormandy discovered a heap overflow flaw during video-to-video copy operations in the Cirrus VGA extension code that is used in Xen.
A malicious local administrator of a guest domain could potentially trigger this flaw and execute arbitrary code outside of the domain (CVE-2007-1320).

Tavis Ormandy also discovered insufficient input validation leading to a heap overflow in the NE2000 network driver in Xen. If the driver is in use, a malicious local administrator of a guest domain could potentially trigger this flaw and execute arbitrary code outside of the domain (CVE-2007-1321, CVE-2007-5729, CVE-2007-5730).

Steve Kemp found that xen-utils used insecure temporary files within the xenmon tool that could allow local users to truncate arbitrary files (CVE-2007-3919).

Joris van Rantwijk discovered a flaw in Pygrub, which is used as a boot loader for guest domains. A malicious local administrator of a guest domain could create a carefully-crafted grub.conf file which could trigger the execution of arbitrary code outside of that domain (CVE-2007-4993).

Updated packages have been patched to prevent these issues.

- Fri Oct 26 2007 Daniel P. Berrange <berrange at     redhat.com> - 3.1.0-13.fc6

    - Fixed xenbaked tmpfile flaw (CVE-2007-3919)

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update merges back the Xen version from SLES 10 Service Pack 1 to the 10.1 codebase, which should make it work again.

Nevertheless we recommend Xen users to use the latest openSUSE release (10.3) for Xen usage.

Additionaly a /tmp race was fixed (CVE-2007-3919).

From Red Hat Security Advisory 2008:0194 :

Updated xen packages that fix several security issues and a bug are now available for Red Hat Enterprise Linux 5.

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

The xen packages contain tools for managing the virtual machine monitor in Red Hat Virtualization.

These updated packages fix the following security issues :

Daniel P. Berrange discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the format of messages serving to update the contents of the framebuffer. This could allow a malicious user to cause a denial of service, or compromise the privileged domain (Dom0). (CVE-2008-1944)

Markus Armbruster discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the frontend's framebuffer description. This could allow a malicious user to cause a denial of service, or to use a specially crafted frontend to compromise the privileged domain (Dom0). (CVE-2008-1943)

Chris Wright discovered a security vulnerability in the QEMU block format auto-detection, when running fully-virtualized guests. Such fully-virtualized guests, with a raw formatted disk image, were able to write a header to that disk image describing another format. This could allow such guests to read arbitrary files in their hypervisor's host. (CVE-2008-2004)

Ian Jackson discovered a security vulnerability in the QEMU block device drivers backend. A guest operating system could issue a block device request and read or write arbitrary memory locations, which could lead to privilege escalation. (CVE-2008-0928)

Tavis Ormandy found that QEMU did not perform adequate sanity-checking of data received via the 'net socket listen' option. A malicious local administrator of a guest domain could trigger this flaw to potentially execute arbitrary code outside of the domain. (CVE-2007-5730)

Steve Kemp discovered that the xenbaked daemon and the XenMon utility communicated via an insecure temporary file. A malicious local administrator of a guest domain could perform a symbolic link attack, causing arbitrary files to be truncated. (CVE-2007-3919)

As well, in the previous xen packages, it was possible for Dom0 to fail to flush data from a fully-virtualized guest to disk, even if the guest explicitly requested the flush. This could cause data integrity problems on the guest. In these updated packages, Dom0 always respects the request to flush to disk.

Users of xen are advised to upgrade to these updated packages, which resolve these issues.

Note: Troy Dawson has tested this update on a machine hosting both paravirtualized and fully virtualized machines, both 32 bit and 64 bit. He did the update while all the machines were running, none of them had any problems. He also tried stopping, starting, and rebooting several of the machines. All without any problems. We tell you this because updating the xen package, while running virtual machines, can make you a little nervous.

These updated packages fix the following security issues :

Daniel P. Berrange discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the format of messages serving to update the contents of the framebuffer. This could allow a malicious user to cause a denial of service, or compromise the privileged domain (Dom0). (CVE-2008-1944)

Markus Armbruster discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the frontend's framebuffer description. This could allow a malicious user to cause a denial of service, or to use a specially crafted frontend to compromise the privileged domain (Dom0). (CVE-2008-1943)

Chris Wright discovered a security vulnerability in the QEMU block format auto-detection, when running fully-virtualized guests. Such fully-virtualized guests, with a raw formatted disk image, were able to write a header to that disk image describing another format. This could allow such guests to read arbitrary files in their hypervisor's host. (CVE-2008-2004)

Ian Jackson discovered a security vulnerability in the QEMU block device drivers backend. A guest operating system could issue a block device request and read or write arbitrary memory locations, which could lead to privilege escalation. (CVE-2008-0928)

Tavis Ormandy found that QEMU did not perform adequate sanity-checking of data received via the 'net socket listen' option. A malicious local administrator of a guest domain could trigger this flaw to potentially execute arbitrary code outside of the domain. (CVE-2007-5730)

Steve Kemp discovered that the xenbaked daemon and the XenMon utility communicated via an insecure temporary file. A malicious local administrator of a guest domain could perform a symbolic link attack, causing arbitrary files to be truncated. (CVE-2007-3919)

As well, in the previous xen packages, it was possible for Dom0 to fail to flush data from a fully-virtualized guest to disk, even if the guest explicitly requested the flush. This could cause data integrity problems on the guest. In these updated packages, Dom0 always respects the request to flush to disk.

The remote Redhat Enterprise Linux 5 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2008:0194 advisory.

  - xen xenmon.py / xenbaked insecure temporary file accesss (CVE-2007-3919)

  - QEMU Buffer overflow via crafted net socket listen option (CVE-2007-5730)

  - Qemu insufficient block device address range checking (CVE-2008-0928)

  - PVFB backend fails to validate frontend's framebuffer description (CVE-2008-1943)

  - PVFB SDL backend chokes on bogus screen updates (CVE-2008-1944)

  - qemu/kvm/xen: qemu block format auto-detection vulnerability (CVE-2008-2004)

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

Updated xen packages that fix several security issues and a bug are now available for Red Hat Enterprise Linux 5.

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

The xen packages contain tools for managing the virtual machine monitor in Red Hat Virtualization.

These updated packages fix the following security issues :

Daniel P. Berrange discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the format of messages serving to update the contents of the framebuffer. This could allow a malicious user to cause a denial of service, or compromise the privileged domain (Dom0). (CVE-2008-1944)

Markus Armbruster discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the frontend's framebuffer description. This could allow a malicious user to cause a denial of service, or to use a specially crafted frontend to compromise the privileged domain (Dom0). (CVE-2008-1943)

Chris Wright discovered a security vulnerability in the QEMU block format auto-detection, when running fully-virtualized guests. Such fully-virtualized guests, with a raw formatted disk image, were able to write a header to that disk image describing another format. This could allow such guests to read arbitrary files in their hypervisor's host. (CVE-2008-2004)

Ian Jackson discovered a security vulnerability in the QEMU block device drivers backend. A guest operating system could issue a block device request and read or write arbitrary memory locations, which could lead to privilege escalation. (CVE-2008-0928)

Tavis Ormandy found that QEMU did not perform adequate sanity-checking of data received via the 'net socket listen' option. A malicious local administrator of a guest domain could trigger this flaw to potentially execute arbitrary code outside of the domain. (CVE-2007-5730)

Steve Kemp discovered that the xenbaked daemon and the XenMon utility communicated via an insecure temporary file. A malicious local administrator of a guest domain could perform a symbolic link attack, causing arbitrary files to be truncated. (CVE-2007-3919)

As well, in the previous xen packages, it was possible for Dom0 to fail to flush data from a fully-virtualized guest to disk, even if the guest explicitly requested the flush. This could cause data integrity problems on the guest. In these updated packages, Dom0 always respects the request to flush to disk.

Users of xen are advised to upgrade to these updated packages, which resolve these issues.

Steve Kemp from the Debian Security Audit project discovered that xen-utils, a collection of XEN administrative tools, used temporary files insecurely within the xenmon tool allowing local users to truncate arbitrary files.

- Fri Oct 26 2007 Daniel P. Berrange <berrange at     redhat.com> - 3.1.0-8.fc7

    - Fixed xenbaked tmpfile flaw (CVE-2007-3919)

    - Wed Sep 26 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-7.fc7

    - Fixed rtl8139 checksum calculation for Vista (rhbz       #308201)

    - Wed Sep 26 2007 Chris Lalancette <clalance at       redhat.com> - 3.1.0-6.fc7

    - QEmu NE2000 overflow check - CVE-2007-1321

    - Pygrub guest escape - CVE-2007-4993

    - Mon Sep 24 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-5.fc7

    - Fix generation of manual pages (rhbz #250791)

    - Fix 32-on-64 PVFB for FC6 legacy guests

    - Mon Sep 24 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-4.fc7

    - Fix VMX assist IRQ handling (rhbz #279581)

    - Sun Sep 23 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-3.fc7

    - Don't clobber the VIF type attribute in FV guests       (rhbz #247122)

    - Wed Aug 1 2007 Markus Armbruster <armbru at       redhat.com>

    - Put guest's native protocol ABI into xenstore, to       provide for older kernels running 32-on-64.

  - VNC keymap fixes

    - Fix race conditions in LibVNCServer on client       disconnect

    - Mon Jun 11 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-2.fc7

    - Remove patch which kills VNC monitor

    - Fix HVM save/restore file path to be /var/lib/xen       instead of /tmp

    - Don't spawn a bogus xen-vncfb daemon for HVM guests

    - Fri May 25 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-1.fc7

    - Updated to official 3.1.0 tar.gz

    - Fixed data corruption from VNC client disconnect (bz       241303)

    - Thu May 17 2007 Daniel P. Berrange <berrange at       redhat.com> - 3.1.0-0.rc7.2.fc7

    - Ensure xen-vncfb processes are cleanedup if guest       quits (bz 240406)

    - Tear down guest if device hotplug fails

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Published	Updated	Severity
27614	Mandrake Linux Security Advisory : xen (MDKSA-2007:203)	Nessus	Mandriva Local Security Checks	11/2/2007	1/6/2021	high
27636	Fedora Core 6 : xen-3.0.3-13.fc6 (2007-737)	Nessus	Fedora Local Security Checks	11/6/2007	1/11/2021	medium
28207	openSUSE 10 Security Update : xen (xen-4616)	Nessus	SuSE Local Security Checks	11/14/2007	1/14/2021	medium
67671	Oracle Linux 5 : xen (ELSA-2008-0194)	Nessus	Oracle Linux Local Security Checks	7/12/2013	1/14/2021	high
60398	Scientific Linux Security Update : xen on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	8/1/2012	1/14/2021	high
32354	RHEL 5 : xen (RHSA-2008:0194)	Nessus	Red Hat Local Security Checks	5/16/2008	4/21/2024	high
43678	CentOS 5 : xen (CESA-2008:0194)	Nessus	CentOS Local Security Checks	1/6/2010	1/4/2021	high
27577	Debian DSA-1395-1 : xen-utils - insecure temporary files	Nessus	Debian Local Security Checks	10/26/2007	1/4/2021	medium
27794	Fedora 7 : xen-3.1.0-8.fc7 (2007-2708)	Nessus	Fedora Local Security Checks	11/6/2007	1/11/2021	medium

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