To: bugtraqat_private announceat_private scoannmodat_private ___________________________________________________________________________ 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 ___________________________________________________________________________ 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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