Risks
FreeBSD Security Advisory - Insufficient range checking of signal numbers (revised)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
=============================================================================
FreeBSD-SA-03:09.signal Security Advisory
The FreeBSD Project
Topic: Insufficient range checking of signal numbers
Category: core
Module: sys
Announced: 2003-08-10
Affects: All releases of FreeBSD up to and including 4.8-RELEASE-p1,
5.1-RELEASE (but see `Impact' below)
FreeBSD 4-STABLE prior to the correction date
Corrected: 2003-08-10 23:09:28 UTC (RELENG_4)
2003-08-10 23:14:08 UTC (RELENG_5_1)
2003-08-10 23:17:48 UTC (RELENG_5_0)
2003-08-10 23:19:35 UTC (RELENG_4_8)
2003-08-11 10:14:38 UTC (RELENG_4_7)
2003-08-11 10:16:35 UTC (RELENG_4_6)
2003-08-12 20:23:24 UTC (RELENG_4_5)
2003-08-12 20:23:51 UTC (RELENG_4_4)
2003-08-12 20:24:13 UTC (RELENG_4_3)
FreeBSD only: YES
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/>.
0. Revision History
v1.0 2003-08-10 Initial release
v1.1 2003-08-11 Updated correction details for RELENG_4_7,
RELENG_4_6, RELENG_4_5, RELENG_4_4, RELENG_4_3
branches. Corrected an internal section reference.
Corrected a source file path name.
I. Background
Signals are a UNIX mechanism for handling asynchronous events such as
pressing the terminal interrupt key (e.g. Ctrl-C), job control, memory
access violations, I/O completion, and many others. Each signal is
assigned a positive number. There are a number of mechanisms by which
a process may cause a signal to be sent, including using the kill(2)
system call or registering with certain device drivers.
II. Problem Description
Some mechanisms for causing a signal to be sent did not properly
validate the signal number, in some cases allowing the kernel to
attempt to deliver a negative or out-of-range signal number. Such
errors were present in the ptrace(2) system call and the `spigot'
video capture device driver.
The error in ptrace(2) was introduced in FreeBSD version 4.2-RELEASE
(4-STABLE dated Oct 26 04:34:41 2000 UTC).
The `spigot' device driver (including the error) was introduced in
FreeBSD 2.0.5. It has never been included in the kernel installed by
default, nor in the GENERIC kernel configuration. Only systems with
`device spigot' added to the kernel configuration are affected by this
instance of the error.
III. Impact
In most cases, attempted delivery of a negative or out-of-range signal
number will trigger an assertion failure and panic, thereby crashing
the system. A malicious local user could use this vulnerability
as a local denial-of-service attack.
However, in FreeBSD 5.x, the assertion code is not present if the
`INVARIANTS' kernel option is not used. In FreeBSD 5.0-RELEASE and
5.1-RELEASE, `INVARIANTS' is not enabled by default. In this
configuration, a malicious local user could use this vulnerability
to modify kernel memory, potentially leading to complete system
compromise. (FreeBSD 4.x is not vulnerable in this way.)
IV. Workaround
There is no workaround for the local denial-of-service attack.
The more severe impact, present only in FreeBSD 5.x systems, can be
avoided by uncommenting or adding the `INVARIANTS' line to your kernel
configuration:
options INVARIANTS #Enable calls of extra sanity checking
Recompile your kernel as described in
<URL:http://www.freebsd.org/handbook/kernelconfig.html>
and reboot the system.
NOTE WELL: This workaround is only for FreeBSD 5.x systems. This
workaround does not eliminate the possibility of a local
denial-of-service attack.
V. Solution
1) Upgrade your vulnerable system to 4.8-STABLE, or to any of the
RELENG_4_8 (4.8-RELEASE-p2), RELENG_4_7 (4.7-RELEASE-p12), or
RELENG_5_1 (5.1-RELEASE-p1) security branches dated after the
respective correction dates.
2) To patch your present system:
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 5.1-RELEASE]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal51.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal51.patch.asc
[FreeBSD 5.0-RELEASE]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal50.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal50.patch.asc
[FreeBSD 4.8-RELEASE, 4.8-STABLE, 4.7-STABLE dated Jan 2 20:39:13 2003 UTC
or later]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal4s.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal4s.patch.asc
[FreeBSD 4.3-RELEASE through 4.7-RELEASE, 4.7-STABLE dated before
Jan 2 20:39:13 2003 UTC]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal47.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal47.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.
VI. Correction details
The following list contains the revision numbers of each file that was
corrected in FreeBSD.
Branch Revision
Path
- -------------------------------------------------------------------------
src/sys/UPDATING
RELENG_5_1 1.251.2.2
RELENG_5_0 1.229.2.15
RELENG_4_8 1.73.2.80.2.4
RELENG_4_7 1.73.2.74.2.15
RELENG_4_6 1.73.2.68.2.43
RELENG_4_5 1.73.2.50.2.45
RELENG_4_4 1.73.2.43.2.46
RELENG_4_3 1.73.2.28.2.33
src/sys/conf/newvers.sh
RELENG_5_1 1.50.2.3
RELENG_5_0 1.48.2.10
RELENG_4_8 1.44.2.29.2.3
RELENG_4_7 1.44.2.26.2.14
RELENG_4_6 1.44.2.23.2.32
RELENG_4_5 1.44.2.20.2.29
RELENG_4_4 1.44.2.17.2.37
RELENG_4_3 1.44.2.14.2.23
src/sys/i386/isa/spigot.c
RELENG_4 1.44.2.1
RELENG_5_1 1.58.2.1
RELENG_5_0 1.55.2.1
RELENG_4_8 1.44.14.1
RELENG_4_7 1.44.12.1
RELENG_4_6 1.44.10.1
RELENG_4_5 1.44.8.1
RELENG_4_4 1.44.6.1
RELENG_4_3 1.44.4.1
src/sys/kern/sys_process.c
RELENG_4 1.51.2.7
RELENG_5_1 1.108.2.1
RELENG_5_0 1.104.2.1
RELENG_4_8 1.51.2.6.2.1
RELENG_4_7 1.51.2.4.2.2
RELENG_4_6 1.51.2.3.4.2
RELENG_4_5 1.51.2.3.2.2
RELENG_4_4 1.51.2.1.4.3
RELENG_4_3 1.51.2.1.2.3
src/sys/kern/kern_sig.c
RELENG_5_1 1.239.2.1
RELENG_5_0 1.197.2.1
- -------------------------------------------------------------------------
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.2 (FreeBSD)
iD8DBQE/OVDMFdaIBMps37IRAsaBAJ4zAzw4sDcu2oc/M7iiXfLQzg8WogCeNqeF
Di+jeJfFrpGAh+/JxUAW/60=
=qXMR
-----END PGP SIGNATURE-----
Spotlight
Is it time to professionalize information security?
Posted on 23 May 2013. | The issue of whether or not information security professionals should be licensed to practice has already been the topic of many a passionate debate.
Review: Logging and Log Management
Posted on 22 May 2013. | Every security practitioner should be aware of the overwhelming advantages of logging and perusing logs for discovering system intrusions. But logging and log management comes with its own set of difficulties.
Experts highlight top data breach vulnerabilities
Posted on 22 May 2013. | Hidden vulnerabilities lie in everyday activities that can expose personal information and lead to data breach, including buying gas with a credit card or wearing a pacemaker.
A closer look at Mega cloud storage
Posted on 21 May 2013. | Once a novelty, nowadays many cloud storage services are fighting for their piece of the market in the virtual world. Mega offers 50GB of free space with great pricing on Pro accounts.
The CSO perspective on healthcare security and compliance
Posted on 20 May 2013. | Randall Gamby is the CSO of the Medicaid Information Service Center of New York. In this interview he discusses healthcare security and compliance challenges and offers a variety of tips.
Daily digest
By subscribing to our early morning news update, you will receive a daily digest of the latest security news published on Help Net Security.
By subscribing to our early morning news update, you will receive a daily digest of the latest security news published on Help Net Security.
Weekly newsletter
With over 500 issues so far, reading our newsletter every Monday morning will keep you up-to-date with security risks out there.
With over 500 issues so far, reading our newsletter every Monday morning will keep you up-to-date with security risks out there.
 |
