[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] Xen Security Advisory 66 (CVE-2013-4361) - Information leak through fbld instruction emulation



-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

              Xen Security Advisory CVE-2013-4361 / XSA-66
                              version 3

           Information leak through fbld instruction emulation

UPDATES IN VERSION 3
====================

Public Release.

ISSUE DESCRIPTION
=================

The emulation of the fbld instruction (which is used during I/O
emulation) uses the wrong variable for the source effective address.
As a result, the actual address used is an uninitialised bit pattern
from the stack.

A malicious guest might be able to find out information about the
contents of the hypervisor stack, by observing which values are
actually being used by fbld and inferring what the address must have
been.  Depending on the actual values on the stack this attack might
be very difficult to carry out.

IMPACT
======

A malicious guest might conceivably gain access to sensitive data
relating to other guests.

VULNERABLE SYSTEMS
==================

Xen 3.3.x and later are vulnerable.

Only HVM guests can take advantage of this vulnerability.

MITIGATION
==========

Running only PV guests will avoid this issue.

There is no mitigation available for HVM guests.  We believe this
vulnerability would require significant research to exploit.

CREDITS
=======

Jan Beulich discovered this issue.

RESOLUTION
==========

Applying the attached patch resolves this issue.

xsa66.patch             Xen 4.2.x, Xen 4.3.x, xen-unstable


$ sha256sum xsa66.patch
3a9b6bf114eb19d708b68dd5973763ac83b57840bc0f6fbd1fe487797eaffed4  xsa66.patch
$
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)

iQEcBAEBAgAGBQJSSUhOAAoJEIP+FMlX6CvZdTsIAISzxoVv5PVKcT3RlikuDPdS
AN4b5d/AJHGUcVg0K8CAd5UpvP0y5UfVhMFc+LCNDoeTE6a+4PsS/2V49HX259tT
oX1HDZUxzfDbNTgZL5/hS3RUNZvTlWxVS0E5SMRW5jDrScPFUOqliD9hNj2cyvlq
Ne362V5VFFb9AcZsMPnl2V4FerUyyuTCncxcvsvDshFIhBaqBY8G/LBqIHE7CKZF
qCK9688RIMlwgNag7fbSloCLOifC7Jrfp9k+wfhAUdLj6R6l2SuyItYa7KufTAof
/bWddQVFxhxcapYMDiNExZNxbHoM51rAeSkC3eYn6BGWKjqfIetA4X+uzfP3LNc=
=PSEF
-----END PGP SIGNATURE-----

Attachment: xsa66.patch
Description: Binary data

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.