FreeBSD Hyper-Threading Technology Support May Disclose Information to Local Users
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SecurityTracker Alert ID: 1013967 |
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SecurityTracker URL: http://securitytracker.com/id/1013967
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CVE Reference:
CVE-2005-0109
(Links to External Site)
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Updated: Jun 2 2006
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Original Entry Date: May 13 2005
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Impact:
Disclosure of authentication information, Disclosure of system information, Disclosure of user information, Root access via local system, User access via local system
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Fix Available: Yes Vendor Confirmed: Yes
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Version(s): 5.4 and prior versions
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Description:
A vulnerability was reported in FreeBSD when using Hyper-Threading Technology. A local user may be able to obtain elevated privileges.
A local user may be able to obtain potentially sensitive information. In "many cases," this may be exploited to gain elevated privileges.
The vendor credits Colin Percival with reporting this vulnerability.
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Impact:
A local user may be able to obtain information, leading to privilege escalation.
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Solution:
The vendor has described the following solution [quoted]:
1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the RELENG_5_4, RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch dated after the correction date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 4.10, 4.11, 5.3, and 5.4 systems.
a) Download the relevant patch from the location below and verify the detached PGP signature using your PGP utility.
[FreeBSD 4.10]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt410.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt410.patch.asc
[FreeBSD 4.11]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt411.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt411.patch.asc
[FreeBSD 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch.asc
b) Apply the patch.
# cd /usr/src
# patch < /path/to/patch
c) Recompile your kernel as described in <URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the system.
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Vendor URL: www.freebsd.org/security/ (Links to External Site)
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Cause:
Access control error
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Subject: FreeBSD Security Advisory FreeBSD-SA-05:09.htt
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
=============================================================================
FreeBSD-SA-05:09.htt Security Advisory
The FreeBSD Project
Topic: information disclosure when using HTT
Category: core
Module: sys
Announced: 2005-05-13
Revised: 2005-05-13
Credits: Colin Percival
Affects: All FreeBSD/i386 and FreeBSD/amd64 releases.
Corrected: 2005-05-13 00:13:00 UTC (RELENG_5, 5.4-STABLE)
2005-05-13 00:13:00 UTC (RELENG_5_4, 5.4-RELEASE-p1)
2005-05-13 00:13:00 UTC (RELENG_5_3, 5.3-RELEASE-p15)
2005-05-13 00:13:00 UTC (RELENG_4, 4.11-STABLE)
2005-05-13 00:13:00 UTC (RELENG_4_11, 4.11-RELEASE-p9)
2005-05-13 00:13:00 UTC (RELENG_4_10, 4.10-RELEASE-p14)
CVE Name: CAN-2005-0109
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.
I. Background
"Hyper-Threading Technology" is the name used for the implementation of
simultaneous multithreading on Intel Pentium 4, Mobile Pentium 4, and
Xeon processors.
II. Problem Description
A security flaw involving operating systems running on Hyper-Threading
Technology processors was has been reported. Complete details are not
available at the time of this writing. However, a workaround has been
issued. It is expected that more details will be available tomorrow, at
which time a revised version of this advisory will be published.
III. Impact
Information may be disclosed to local users, allowing in many cases for
privilege escalation.
IV. Workaround
Systems not using processors with Hyper-Threading support are not
affected by this issue. On systems which are affected, the security
flaw can be eliminated by setting the "machdep.hlt_logical_cpus"
tunable:
# echo "machdep.hlt_logical_cpus=1" >> /boot/loader.conf
The system must be rebooted in order for tunables to take effect.
Use of this workaround is not recommended on "dual-core" systems, as
this workaround will also disable one of the processor cores.
V. Solution
Perform one of the following:
1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
RELENG_5_4, RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch
dated after the correction date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 4.10,
4.11, 5.3, and 5.4 systems.
a) Download the relevant patch from the location below and verify the
detached PGP signature using your PGP utility.
[FreeBSD 4.10]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt410.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt410.patch.asc
[FreeBSD 4.11]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt411.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt411.patch.asc
[FreeBSD 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:09/htt5.patch.asc
b) Apply the patch.
# cd /usr/src
# patch < /path/to/patch
c) Recompile your kernel as described in
<URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the
system.
NOTE: For users that are certain that their environment is not affected
by this vulnerability, such as single-user systems, Hyper-Threading
Technology may be re-enabled by setting the tunable
"machdep.hyperthreading_allowed".
VI. Correction details
The following list contains the revision numbers of each file that was
corrected in FreeBSD.
Branch Revision
Path
- -------------------------------------------------------------------------
RELENG_4
src/sys/i386/i386/mp_machdep.c 1.115.2.23
src/sys/i386/include/cpufunc.h 1.96.2.4
RELENG_4_11
src/UPDATING 1.73.2.91.2.10
src/sys/conf/newvers.sh 1.44.2.39.2.13
src/sys/i386/i386/mp_machdep.c 1.115.2.22.2.1
src/sys/i386/include/cpufunc.h 1.96.2.3.12.1
RELENG_4_10
src/UPDATING 1.73.2.90.2.15
src/sys/conf/newvers.sh 1.44.2.34.2.16
src/sys/i386/i386/mp_machdep.c 1.115.2.20.2.1
src/sys/i386/include/cpufunc.h 1.96.2.3.10.1
RELENG_5
src/sys/amd64/amd64/mp_machdep.c 1.242.2.11
src/sys/amd64/include/cpufunc.h 1.145.2.1
src/sys/i386/i386/mp_machdep.c 1.235.2.10
src/sys/i386/include/cpufunc.h 1.142.2.1
RELENG_5_4
src/UPDATING 1.342.2.24.2.10
src/sys/amd64/amd64/mp_machdep.c 1.242.2.7.2.4
src/sys/amd64/include/cpufunc.h 1.145.6.1
src/sys/conf/newvers.sh 1.62.2.18.2.6
src/sys/i386/i386/mp_machdep.c 1.235.2.6.2.3
src/sys/i386/include/cpufunc.h 1.142.6.1
RELENG_5_3
src/UPDATING 1.342.2.13.2.18
src/sys/amd64/amd64/mp_machdep.c 1.242.2.2.2.2
src/sys/amd64/include/cpufunc.h 1.145.4.1
src/sys/conf/newvers.sh 1.62.2.15.2.20
src/sys/i386/i386/mp_machdep.c 1.235.2.3.2.2
src/sys/i386/include/cpufunc.h 1.142.4.1
- -------------------------------------------------------------------------
VII. References
http://www.daemonology.net/hyperthreading-considered-harmful/
The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:09.htt.asc
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