(1) xenbaked and (2) xenmon.py in Xen 3.1 and earlier allow local users to truncate arbitrary files via a symlink attack on /tmp/xenq-shm.

The remote MiracleLinux 3 host has packages installed that are affected by multiple vulnerabilities as referenced in the AXSA:2008-443:02 advisory.

    This package contains the Xen tools and management daemons needed to run virtual machines.
    Information on how to use Xen can be found at the Xen project pages.
    The Xen system also requires the Xen hypervisor and domain-0 kernel, which can be found in the kernel-xen*     package.
    Virtualization can be used to run multiple operating systems on one physical system, for purposes of     hardware consolidation, hardware abstraction, or to test untrusted applications in a sandboxed     environment.
    Bugs fixed:
    CVE-2007-4993     pygrub (tools/pygrub/src/GrubConf.py) in Xen 3.0.3, when booting a guest domain, allows local users with     elevated privileges in the guest domain to execute arbitrary commands in domain 0 via a crafted grub.conf     file whose contents are used in exec statements.
    CVE-2007-1321     Integer signedness error in the NE2000 emulator in QEMU 0.8.2, as used in Xen and possibly other products,     allows local users to trigger a heap-based buffer overflow via certain register values that bypass sanity     checks, aka QEMU NE2000 receive integer signedness error. NOTE: this identifier was inadvertently used     by some sources to cover multiple issues that were labeled NE2000 network driver and the socket code,     but separate identifiers have been created for the individual vulnerabilities since there are sometimes     different fixes; see CVE-2007-5729 and CVE-2007-5730.
    CVE-2007-3919     (1) xenbaked and (2) xenmon.py in Xen 3.1 and earlier allow local users to truncate arbitrary files via a     symlink attack on /tmp/xenq-shm.
    CVE-2008-0928     Qemu 0.9.1 and earlier does not perform range checks for block device read or write requests, which allows     guest host users with root privileges to access arbitrary memory and escape the virtual machine.
    CVE-2007-5730     Heap-based buffer overflow in QEMU 0.8.2, as used in Xen and possibly other products, allows local users     to execute arbitrary code via crafted data in the net socket listen option, aka QEMU net socket heap     overflow. NOTE: some sources have used CVE-2007-1321 to refer to this issue as part of NE2000 network     driver and the socket code, but this is the correct identifier for the individual net socket listen     vulnerability.
    CVE-2008-2004     The drive_init function in QEMU 0.9.1 determines the format of a raw disk image based on the header, which     allows local guest users to read arbitrary files on the host by modifying the header to identify a     different format, which is used when the guest is restarted.
    CVE-2008-1945     QEMU 0.9.0 does not properly handle changes to removable media, which allows guest OS users to read     arbitrary files on the host OS by using the diskformat: parameter in the -usbdevice option to modify the     disk-image header to identify a different format, a related issue to CVE-2008-2004.
    CVE-2008-1952     The backend for XenSource Xen Para Virtualized Frame Buffer (PVFB) in Xen ioemu does not properly restrict     the frame buffer size, which allows attackers to cause a denial of service (crash) by mapping an arbitrary     amount of guest memory.
    - rebuild for Asianux 3.0 SP1
    - use functions for service script xendomains by default
    - Fix PVFB to validate frame buffer description
    - Fix PVFB to cope with bogus update requests
    - Fix FV O_DIRECT flushing
    - Rewrite locking in hotplug scripts to fix timeouts
    - Require xen-hypervisor-abi = 3.1 to pull in neccessary kernel
    - Fixed memory ballooning for HVM restore
    - Avoid bogus VNC password prompts after migrate/restore
    - Fix UUID normalization when no UUID is present
    - Fix handling of 'keymap' param in config files
    - Don't destroy guest after shutdown timeout
    - Ensure PVFB daemon terminates promptly on domain shutdown
    - Fix rtl8139 checksums for VISTA
    - Update package description to better reflect reality
    - Fix more VNC threading problems
    - Fix save/restore edge case
    - Fix legacy PVFB for 32-on-64
    - Fixed booting guests with legacy native ABI device protocol
    - Fix more VNC keycode/keysym mappings issues
    - Fix potential QEMU crash when VNC client disconnects
    - Add NVRAM support for ia64 guests
    - Normalize UUID to avoid loosing guest name upon restarts
    - fix ethernet bonding in balanced-rr mode
    - Fix vncport type cast for HVM guests
    - Ignore failures in dump core
    - Rate limit console messages from guest
    - Use -r flag to losetup for readonly block devices
    - Mark /etc/sysconfig/xend as a config file
    - Fix address test in network-bridge
    - Permissions of xend-debug.log
    - Hotplug scripts error reporting
    - Disable network-bridge if running on Dom0 with nfs/iscsi root device
    - Fix a race in the pvfb startup
    - Loadable pvfb keymap
    - Fix pvfb save/restore broken in 3.0.3-27.el5
    - Fixed 32-bit core dumps with HVM
    - Add persistent logging of guest & hypervisor console
    - Fix destroyDevice() args
    - Check file exists in blktap hotplug scripts
    - Make SXPR server in XenD multi-threaded
    - Fixed xm man page about block device modes
    - Update low level (non-XenD) userspace to work with 3.1.0 hypervisor
    - Patch XenD to use 'domid' instead of 'dom' with libxc
    - Patch XenD to use new HVM domain creation process
    - Remove unused i18n stuff from Makefile
    - Fix pygrub, blktapctrl paths to return to original settings
    - Back-port 3.1.0 HVM save/restore changes to XenD
    - Move HVM save/restore files from /tmp to /var/lib/xen
    - Ensure pvfb backend terminates when frontend vanishes early
    - Save vncpasswd in xenstore along with the other pvfb configuration
    - Fix allocation of fixed VNC ports for pvfb
    - Don't start a xen-vncfb process for HVM
    - disable qemu monitor mode, for security reasons
    - fix IA64 shadow page table mode

Tenable has extracted the preceding description block directly from the MiracleLinux security advisory.

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

The remote MiracleLinux 3 host has packages installed that are affected by multiple vulnerabilities as referenced in the AXSA:2008-256:01 advisory.

    This package contains the Xen tools and management daemons needed to run virtual machines on x86, x86_64,     and ia64 systems.
    Information on how to use Xen can be found at the Xen project pages.
    The Xen system also requires the Xen hypervisor and domain-0 kernel, which can be found in the kernel-xen*     package.
    Virtualization can be used to run multiple operating systems on one physical system, for purposes of     hardware consolidation, hardware abstraction, or to test untrusted applications in a sandboxed     environment.
    - rebuild for Asianux 3.0 SP1
    - add patch700 to use functions for service script xendomains by default
    - modify redhat string to asianux (#2837, Patch701)
    - Disable QEMU image format auto-detection CVE-2008-2004
    - Fix PVFB to validate frame buffer description
    - Fix PVFB to cope with bogus update requests
    - Fix QEMU buffer overflow CVE-2007-5730
    - Fix QEMU block device extents checking CVE-2008-0928
    - Fix FV O_DIRECT flushing
    - Fixed xenbaked tmpfile flaw (CVE-2007-3919
    - QEmu NE2000 overflow check - CVE-2007-1321
    - Pygrub guest escape - CVE-2007-4993
    - Rewrite locking in hotplug scripts to fix timeouts
    - Require xen-hypervisor-abi = 3.1 to pull in neccessary kernel
    - Fixed memory ballooning for HVM restore
    - Avoid bogus VNC password prompts after migrate/restore
    - Fix UUID normalization when no UUID is present
    - Fix handling of 'keymap' param in config files
    - Don't destroy guest after shutdown timeout
    - Ensure PVFB daemon terminates promptly on domain shutdown
    - Fix rtl8139 checksums for VISTA
    - Update package description to better reflect reality
    - Fix more VNC threading problems
    - Fix save/restore edge case
    - Fix legacy PVFB for 32-on-64
    - Fixed booting guests with legacy native ABI device protocol
    - Fix more VNC keycode/keysym mappings issues
    - Fix potential QEMU crash when VNC client disconnects
    - Add NVRAM support for ia64 guests
    - Normalize UUID to avoid loosing guest name upon restarts
    - fix ethernet bonding in balanced-rr mode
    - Fix vncport type cast for HVM guests
    - Ignore failures in dump core
    - Rate limit console messages from guest
    - Use -r flag to losetup for readonly block devices
    - Mark /etc/sysconfig/xend as a config file
    - Fix address test in network-bridge
    - Permissions of xend-debug.log
    - Hotplug scripts error reporting
    - Disable network-bridge if running on Dom0 with nfs/iscsi root device
    - Fix a race in the pvfb startup
    - Loadable pvfb keymap
    - Fix pvfb save/restore broken in 3.0.3-27.el5
    - Fixed 32-bit core dumps with HVM
    - Add persistent logging of guest & hypervisor console
    - Fix destroyDevice() args
    - Check file exists in blktap hotplug scripts
    - Make SXPR server in XenD multi-threaded
    - Fixed xm man page about block device modes
    - Update low level (non-XenD) userspace to work with 3.1.0 hypervisor
    - Patch XenD to use 'domid' instead of 'dom' with libxc
    - Patch XenD to use new HVM domain creation process
    - Remove unused i18n stuff from Makefile
    - Fix pygrub, blktapctrl paths to return to original settings
    - Back-port 3.1.0 HVM save/restore changes to XenD
    - Move HVM save/restore files from /tmp to /var/lib/xen
    - Ensure pvfb backend terminates when frontend vanishes early
    - Save vncpasswd in xenstore along with the other pvfb configuration
    - Fix allocation of fixed VNC ports for pvfb
    - Don't start a xen-vncfb process for HVM
    - disable qemu monitor mode, for security reasons
    - fix IA64 shadow page table mode

Tenable has extracted the preceding description block directly from the MiracleLinux security advisory.

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

The remote Oracle Linux 5 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2008-0194 advisory.

    - Disable QEMU image format auto-detection CVE-2008-2004 (rhbz #444700)
    - Fix QEMU buffer overflow CVE-2007-5730 (rhbz #360381)
    - Fix QEMU block device extents checking CVE-2008-0928 (rhbz #433560)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

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

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.

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.

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.

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).

- 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.

- 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.

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.

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.

ID	Name	Product	Family	Severity
284476	MiracleLinux 3 : xen-3.0.3-64.3.1AXS3 (AXSA:2008-443:02)	Nessus	Miracle Linux Local Security Checks	high
283946	MiracleLinux 3 : xen-3.0.3-41.7AXS3 (AXSA:2008-256:01)	Nessus	Miracle Linux Local Security Checks	high
67671	Oracle Linux 5 : xen (ELSA-2008-0194)	Nessus	Oracle Linux Local Security Checks	high
60398	Scientific Linux Security Update : xen on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	high
43678	CentOS 5 : xen (CESA-2008:0194)	Nessus	CentOS Local Security Checks	high
32354	RHEL 5 : xen (RHSA-2008:0194)	Nessus	Red Hat Local Security Checks	high
28207	openSUSE 10 Security Update : xen (xen-4616)	Nessus	SuSE Local Security Checks	medium
27794	Fedora 7 : xen-3.1.0-8.fc7 (2007-2708)	Nessus	Fedora Local Security Checks	medium
27636	Fedora Core 6 : xen-3.0.3-13.fc6 (2007-737)	Nessus	Fedora Local Security Checks	medium
27614	Mandrake Linux Security Advisory : xen (MDKSA-2007:203)	Nessus	Mandriva Local Security Checks	high
27577	Debian DSA-1395-1 : xen-utils - insecure temporary files	Nessus	Debian Local Security Checks	medium

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CVE-2007-3919

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