Qubes Security Bulletin #8

[Joanna Rutkowska]

---===[ Qubes Security Bulletin #8 ]===---


Problem description
---------------------

Xen.org has announced today a security advisory XSA 58, which fixes a
bug introduced by... a previous security fix identified as XSA 45 (see [1]).

The original problem that the XSA 45 was supposed to fix was a
timing-based DoS attack. Unfortunately the XSA 45 fix, according to the
description in today's advisory, has turned it into a theoretical
privilege escalation bug (so, something much worse, than just some DoS).

Quite fortunately we have not applied XSA 45 patch previously to the Xen
packages released for Qubes R2, so the users, up to date, have only been
affected by the timing DoS, related to XSA 45 problem. Today, we have
released updated Xen packages that apply both patches, hopefully solving
this issue for good.

Patching
----------

We have uploaded the patched Xen packages for Qubes Release 1 (version
4.1.5-2), as well as for the latest Qubes R2 Beta 2 (version 4.1.5-2).
In order to update your system use the following command from Dom0 console:

sudo qubes-dom0-update

A system restart will be required afterwards.

If you use Anti Evil Maid, you will need to reseal your secret
passphrase to new PCR values, as PCR14 will change because of a new
xen.gz binary.


References
------------

[1] http://wiki.xen.org/wiki/Security_Announcements

Thanks,
joanna.

--
The Qubes Security Team
http://wiki.qubes-os.org/trac/wiki/SecurityPage