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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2001.371 -- FreeBSD-SA-01:57.sendmail [REVISED] sendmail contains local root vulnerability 31 August 2001 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: sendmail Operating System: FreeBSD BSD Unix Impact: Root Compromise Access Required: Local Ref: ESB-2001.365 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-01:57 Security Advisory FreeBSD, Inc. Topic: sendmail contains local root vulnerability [REVISED] Category: core Module: sendmail Announced: 2001-08-27 Revised: 2001-08-30 Credits: Cade Cairnss <cairnsc@securityfocus.com> Affects: FreeBSD 4-STABLE after August 27, 2000 and prior to the correction date, FreeBSD 4.1.1-RELEASE, 4.2-RELEASE, 4.3-RELEASE Corrected: 2001-08-21 01:36:37 UTC (FreeBSD 4.3-STABLE) 2001-08-22 05:34:11 UTC (RELENG_4_3) FreeBSD only: NO 0. Revision History v1.0 2001-08-27 Initial release v1.1 2001-08-30 Update package to remove setuid bit from saved file; add non-openssl package; correct typo in package instructions; note that $Id$ not updated in RELENG_4_3. I. Background sendmail is a mail transfer agent. II. Problem Description Sendmail contains an input validation error which may lead to the execution of arbitrary code with elevated privileges by local users. Due to the improper use of signed integers in code responsible for the processing of debugging arguments, a local user may be able to supply the signed integer equivalent of a negative value supplied to sendmail's "trace vector". This may allow a local user to write data anywhere within a certain range of locations in process memory. Because the '-d' command-line switch is processed before the program drops its elevated privileges, the attacker may be able to cause arbitrary code to be executed with root privileges. III. Impact Local users may be able to execute arbitrary code with root privileges. IV. Workaround Do not allow untrusted users to execute the sendmail binary. V. Solution One of the following: 1) Upgrade your vulnerable FreeBSD system to 4.3-STABLE or the RELENG_4_3 security branch after the respective correction dates. 2) FreeBSD 4.x systems after August 27, 2000 and prior to the correction date: The following patch has been verified to apply to FreeBSD 4.1.1-RELEASE, 4.2-RELEASE, 4.3-RELEASE and 4-STABLE dated prior to the correction date. Download the patch and the detached PGP signature from the following locations, and verify the signature using your PGP utility. # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:57/sendmail.patch # fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:57/sendmail.patch.asc Execute the following commands as root: # cd /usr/src # patch -p < /path/to/patch # cd /usr/src/lib/libsmutil # make depend && make all # cd /usr/src/usr.sbin/sendmail # make depend && make all install 3) FreeBSD 4.3-RELEASE systems: ** NOTE: The initial version of the upgrade package did not remove ** setuid root privileges from the saved copy of the sendmail binary. ** To correct this, deinstall the old package using the pkg_delete(1) ** command and install the corrected package as described below. An experimental upgrade package is available for users who wish to provide testing and feedback on the binary upgrade process. This package may be installed on FreeBSD 4.3-RELEASE systems only, and is intended for use on systems for which source patching is not practical or convenient. If you use the upgrade package, feedback (positive or negative) to security-officer@FreeBSD.org is requested so we can improve the process for future advisories. During the installation procedure, backup copies are made of the files which are replaced by the package. These backup copies will be reinstalled if the package is removed, reverting the system to a pre-patched state. Two versions of the package are available, depending on whether or not OpenSSL is installed. If the file /usr/lib/libcrypto.so exists on the local system, follow the directions in section 1a) below, otherwise follow the directions in section 1b). After adding the package, proceed with the instructions in section 2). 1a) If crypto is installed: # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:57/security-patch-sendmail-crypto-01.57.tgz # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:57/security-patch-sendmail-crypto-01.57.tgz.asc Verify the detached PGP signature using your PGP utility. # pkg_add security-patch-sendmail-crypto-01.57.tgz 1b) If crypto is not installed: # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:57/security-patch-sendmail-nocrypto-01.57.tgz # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:57/security-patch-sendmail-nocrypto-01.57.tgz.asc Verify the detached PGP signature using your PGP utility. # pkg_add security-patch-sendmail-nocrypto-01.57.tgz 2) Restart sendmail after applying the patch by executing the following commands as root: # killall sendmail # /usr/sbin/sendmail -bd -q30m The flags to sendmail may need to be adjusted as required for the local system configuration. VI. Correction details The following is the sendmail $Id$ revision number of the file that was corrected for the supported branches of FreeBSD. The $Id$ revision number of the installed source can be examined using the ident(1) command. Note that the $Id$ tag was not updated on the RELENG_4_3 branch because a newer vendor release of sendmail was not imported, instead only this vulnerability was patched. Revision Path 8.20.22.4 src/contrib/sendmail/src/trace.c VII. References <URL:http://www.securityfocus.com/bid/3163> - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (FreeBSD) Comment: For info see http://www.gnupg.org iQCVAwUBO46RWlUuHi5z0oilAQH+VwP+MBpBopVejzWdHAjm0cEslleHZThEjja4 qNd28CAQOy5KAdDcP61pqT2LcxlFUXyjRPjcVo6eqGaO63Lz3Ov2nnm3LPfcyR18 PQaQkezGxTIfORuXxZiNA4EI51zjoquIRVWwMJaR1Azx+vf/u9XPIDVKA7rkL3df wvTf9D4V7ZU= =L1XV - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. This security bulletin is provided as a service to AusCERT's members. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBO4+BJih9+71yA2DNAQFa8gP/RxodKTgafwu6KBx1m2DE4gKfy1dZsgWw Sj3k/fAHTta9SSi4jiidkOwMcMbEX3fEfYUVSgALsbEnomfRVP0UAN7Ho1mq1lMc qaKG7z0IeCqdgwlR4xJ5Rfsc8vZkNw9pzUoQmh8IySAn55sr4pK3ZHJszFgEJFcr rq9AkPw1tKw= =+fzu -----END PGP SIGNATURE-----