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.

The remote OracleVM system is missing necessary patches to address critical security updates :

  - 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

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.

USN-776-1 fixed vulnerabilities in KVM. Due to an incorrect fix, a regression was introduced in Ubuntu 8.04 LTS that caused KVM to fail to boot virtual machines started via libvirt. This update fixes the problem. We apologize for the inconvenience.

Avi Kivity discovered that KVM did not correctly handle certain disk formats. A local attacker could attach a malicious partition that would allow the guest VM to read files on the VM host. (CVE-2008-1945, CVE-2008-2004)

Alfredo Ortega discovered that KVM's VNC protocol handler did not correctly validate certain messages. A remote attacker could send specially crafted VNC messages that would cause KVM to consume CPU resources, leading to a denial of service. (CVE-2008-2382)

Jan Niehusmann discovered that KVM's Cirrus VGA implementation over VNC did not correctly handle certain bitblt operations. A local attacker could exploit this flaw to potentially execute arbitrary code on the VM host or crash KVM, leading to a denial of service. (CVE-2008-4539)

It was discovered that KVM's VNC password checks did not use the correct length. A remote attacker could exploit this flaw to cause KVM to crash, leading to a denial of service.
(CVE-2008-5714).

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

Avi Kivity discovered that KVM did not correctly handle certain disk formats. A local attacker could attach a malicious partition that would allow the guest VM to read files on the VM host. (CVE-2008-1945, CVE-2008-2004)

Alfredo Ortega discovered that KVM's VNC protocol handler did not correctly validate certain messages. A remote attacker could send specially crafted VNC messages that would cause KVM to consume CPU resources, leading to a denial of service. (CVE-2008-2382)

Jan Niehusmann discovered that KVM's Cirrus VGA implementation over VNC did not correctly handle certain bitblt operations. A local attacker could exploit this flaw to potentially execute arbitrary code on the VM host or crash KVM, leading to a denial of service.
(CVE-2008-4539)

It was discovered that KVM's VNC password checks did not use the correct length. A remote attacker could exploit this flaw to cause KVM to crash, leading to a denial of service. (CVE-2008-5714).

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

Multiple vulnerabilities have been found in Qemu.

Multiple heap-based buffer overflows in the cirrus_invalidate_region function in the Cirrus VGA extension in QEMU 0.8.2, as used in Xen and possibly other products, might allow local users to execute arbitrary code via unspecified vectors related to attempting to mark non-existent regions as dirty, aka the bitblt heap overflow.
(CVE-2007-1320)

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.
(CVE-2007-1321)

QEMU 0.8.2 allows local users to halt a virtual machine by executing the icebp instruction. (CVE-2007-1322)

QEMU 0.8.2 allows local users to crash a virtual machine via the divisor operand to the aam instruction, as demonstrated by aam 0x0, which triggers a divide-by-zero error. (CVE-2007-1366)

The NE2000 emulator in QEMU 0.8.2 allows local users to execute arbitrary code by writing Ethernet frames with a size larger than the MTU to the EN0_TCNT register, which triggers a heap-based buffer overflow in the slirp library, aka NE2000 mtu heap overflow.
(CVE-2007-5729)

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. (CVE-2007-5730)

QEMU 0.9.0 allows local users of a Windows XP SP2 guest operating system to overwrite the TranslationBlock (code_gen_buffer) buffer, and probably have unspecified other impacts related to an overflow, via certain Windows executable programs, as demonstrated by qemu-dos.com.
(CVE-2007-6227)

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-2008-0928)

Changing removable media in QEMU could trigger a bug similar to CVE-2008-2004, which would allow local guest users to read arbitrary files on the host by modifying the header of the image to identify a different format. (CVE-2008-1945) See the diskformat: parameter to the
-usbdevice option.

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-2008-2004) See the -format option.

The updated packages have been patched to fix these issues.

Local attackers could use raw formatted disk images to access the hosting environment. CVE-2008-2004 has been assigned to this issue.

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.

Secunia reports :

A vulnerability has been reported in QEMU, which can be exploited by malicious, local users to bypass certain security restrictions.

The vulnerability is caused due to the 'drive_init()' function in vl.c determining the format of a disk from data contained in the disk's header. This can be exploited by a malicious user in a guest system to e.g. read arbitrary files on the host by writing a fake header to a raw formatted disk image.

ID	Name	Product	Family	Severity
79446	OracleVM 2.1 : xen (OVMSA-2008-2003)	Nessus	OracleVM Local Security Checks	medium
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
38777	Ubuntu 8.04 LTS : kvm regression (USN-776-2)	Nessus	Ubuntu Local Security Checks	high
38759	Ubuntu 8.04 LTS / 8.10 : kvm vulnerabilities (USN-776-1)	Nessus	Ubuntu Local Security Checks	high
37509	Mandriva Linux Security Advisory : qemu (MDVSA-2008:162)	Nessus	Mandriva Local Security Checks	high
33163	openSUSE 10 Security Update : qemu (qemu-5270)	Nessus	SuSE Local Security Checks	medium
32354	RHEL 5 : xen (RHSA-2008:0194)	Nessus	Red Hat Local Security Checks	high
32147	FreeBSD : qemu -- 'drive_init()' Disk Format Security Bypass (8950ac62-1d30-11dd-9388-0211060005df)	Nessus	FreeBSD Local Security Checks	medium

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CVE-2008-2004

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