Secunia Security Advisory - Some vulnerabilities have been reported in Xen, which can be exploited by malicious, local users to cause a DoS (Denial of Service).
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TITLE:
Xen DR7 and CR4 Register Handling Denial of Service Vulnerabilities
SECUNIA ADVISORY ID:
SA28405
VERIFY ADVISORY:
http://secunia.com/advisories/28405/
CRITICAL:
Not critical
IMPACT:
DoS
WHERE:
Local system
SOFTWARE:
Xen 3.x
http://secunia.com/product/15863/
DESCRIPTION:
Some vulnerabilities have been reported in Xen, which can be
exploited by malicious, local users to cause a DoS (Denial of
Service).
1) An error within the handling of the DR7 debug register can be
exploited out of a guest system to crash the hypervisor by setting
certain breakpoints.
Successful exploitation may require that a HVM hypervisor is used.
2) Access to the CR4 register is not properly checked. This can be
exploited out of a guest system to e.g. crash DomU or Dom0 domains.
Successful exploitation may require that a paravirtualised kernel is
used.
SOLUTION:
Restrict access to trusted users only.
PROVIDED AND/OR DISCOVERED BY:
Reported by Jan Beulich.
ORIGINAL ADVISORY:
http://lists.xensource.com/archives/html/xen-devel/2007-10/msg01048.html
http://lists.xensource.com/archives/html/xen-devel/2007-10/msg00932.html
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