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Netsikker nu! 2008
 
QEMU Various Vulnerabilities
Secunia Advisory: SA25073
Release Date: 2007-05-01
Last Update: 2008-05-19
Popularity: 7,158 views

Critical:
Moderately critical
Impact: Security Bypass
DoS
Where: Local system
Solution Status: Partial Fix

Software:QEMU 0.x

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CVE reference:CVE-2007-1320
CVE-2007-1321
CVE-2007-1322
CVE-2007-1323
CVE-2007-1366
CVE-2007-5729
CVE-2007-5730
CVE-2007-6227
CVE-2008-0928


Description:
Some vulnerabilities have been reported in QEMU, which can be exploited by malicious, local users to bypass certain security restrictions or cause a DoS (Denial of Service).

1) A boundary error exists within the "cirrus_invalidate_region()" function of the Cirrus video driver, which can be exploited to cause a heap-based buffer overflow.

2) The size of ethernet frames is not correctly checked against the "MTU" before being copied into the registers of the NE2000 network driver. This can be exploited to cause a heap-based buffer overflow.

3) An integer signedness error when processing data in the NE2000 device registers can be exploited to cause a heap-based buffer overflow.

Successful exploitation of 1) through 3) may allow the execution of arbitrary code.

4) Errors when handling the "icebp" instruction can be exploited to cause a DoS by terminating the emulation session.

5) An error within the handling of the "aam" instruction can result in a division by zero, which can be exploited to cause a DoS.

6) A boundary error in "dyngen_code()" when generating host instructions can be exploited to cause a buffer overflow.

7) The block device backends do not properly check a guest's read or write attempts, which can be exploited to e.g. crash the QEMU process or potentially escape the virtualisation jail by writing into arbitrary QEMU host memory.

Successful exploitation of this vulnerability requires privileges to send specially crafted read or write requests to the ioemu block device backends.

Other issues, like an infinite loop in the SB16 driver, the dereference of an uninitialised function in the DMA handling, signedness errors in the IDE handling, and panics in the BIOS and VGA BIOS have also been reported.

Solution:
Vulnerability #1 is fixed in the SVN repository.
http://svn.savannah.gnu.org/viewvc/?view=rev&root=qemu&revision=4340

Do not run untrusted applications in an emulated environment.

Provided and/or discovered by:
1)-5) Tavis Ormandy, Google
6) TeLeMan
7) Ian Jackson

Changelog:
2007-11-02: Added CVE references.
2007-12-03: Added vulnerability #6 and additional link.
2007-12-05: Added CVE reference.
2008-02-26: Added vulnerability #7 and additional link.
2008-02-29: Added CVE reference.
2008-05-19: Updated "Solution" section.

Original Advisory:
Tavis Ormandy:
http://taviso.decsystem.org/virtsec.pdf

http://lists.gnu.org/archive/html/qemu-devel/2007-12/msg00009.html

Ian Jackson:
http://marc.info/?l=debian-security&m=120343592917055&w=2


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