To: bugtraq@securityfocus.com announce@lists.caldera.com scoannmod@xenitec.on.ca
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Caldera International, Inc. Security Advisory
Subject: REVISION: OpenServer: setcontext and sysi86 vulnerabilities
Advisory number: CSSA-2001-SCO.35.1
Issue date: 2001 December 10
Cross reference: CSSA-2001-SCO-35
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1. Problem Description
[ The previous release of this fix was flawed, and required a
recut. If CSSA-2001-SCO-35 has already been applied, Caldera
stongly recommends that you install the updated fix ]
This patch closes a family of security holes present in SCO
OpenServer 5.0.6 and previous releases, which stem from the
ability of regular user processes to reprogram segment
descriptors and certain other CPU registers.
Closing this family of security holes does, however, result in
a functionality change which may prevent certain applications
from running -- they will exit with an error, or dump core,
instead of running properly. For example, the i286emul and
x286emul emulators will not work, so any '286 executables
which require those emulators will not work. It is our
intention to enhance this patch in the future, such that it
enables full functionality of such applications while still
closing the security holes.
If this patch breaks any crucial applications, the system
administrator may choose to disable the patch, by editing the
file /etc/conf/pack.d/kernel/space.c and setting the value of
the allow_dscr_remap parameter to 1. This will return the
kernel to the old (not-secure) behavior.
2. Vulnerable Versions
Operating System Version Affected Files
------------------------------------------------------------------
OpenServer All /etc/conf/pack.d/kernel/os.a(machdep.o)
/etc/conf/pack.d/kernel/os.a(sysi86.o)
3. Workaround
None.
4. OpenServer
4.1 Location of Fixed Binaries
ftp://stage.caldera.com/pub/security/openserver/CSSA-2001-SCO.35.1/
4.2 Verification
md5 checksums:
7d71c8be06a44ec3a3698ee8fbb77375 VOL.000.000
md5 is available for download from
ftp://stage.caldera.com/pub/security/tools/
4.3 Installing Fixed Binaries
Upgrade the affected binaries with the following commands:
Download the VOL.000.000 file to /tmp
# custom
Instruct custom to install from images, and supply /tmp as the
directory of the VOL image.
5. References
ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2001-002.txt.asc
This and other advisories are located at
http://stage.caldera.com/support/security
This advisory addresses Caldera Security internal incidents
sr855993, sr855994, SCO-559-1328, SCO-559-1329, erg711906 and
erg711905.
6. Disclaimer
Caldera International, Inc. is not responsible for the misuse
of any of the information we provide on our website and/or
through our security advisories. Our advisories are a service
to our customers intended to promote secure installation and
use of Caldera International products.
7. Acknowledgements
Caldera wishes to thank the Last Stage of Delirium Research
Group (contact@lsd-pl.net) for their discovering of, and
research into, these issues.
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