Vigil@nce - Xen: information disclosure via AVX/LWP
September 2013 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/offer
SYNTHESIS OF THE VULNERABILITY
An attacker who is located in a guest system can use the
XSAVE/XRSTOR instructions, to read the content of the AVX/LWP
registers of Xen, in order to obtain sensitive information.
Impacted products: Unix (platform)
Severity: 1/4
Creation date: 25/09/2013
DESCRIPTION OF THE VULNERABILITY
The XSAVE and XRSTOR instructions are used to save and restore the
processor state. They are disabled by default in Xen.
The AVX (Advanced Vector Extensions) extensions for x86 processors
and LWP (AMD Lightweight Profiling) are managed by XSAVE/XRSTOR.
However, Xen does not reset their values when the vCPU is changed.
An attacker who is located in a guest system can therefore use the
XSAVE/XRSTOR instructions, to read the content of the AVX/LWP
registers of Xen, in order to obtain sensitive information.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
http://vigilance.fr/vulnerability/Xen-information-disclosure-via-AVX-LWP-13471