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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!spool.mu.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!newsrelay.iastate.edu!ng1.icn.state.ia.us!news.dmacc.cc.ia.us!not-for-mail From: cfr@infoborg.dmacc.cc.ia.us (Charles F. Randall) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Fixed in 2.1.5R? Re: CERT Vendor-Initiated Bulletin VB-96.11 - FreeBSD, Inc. Followup-To: comp.unix.bsd.freebsd.misc Date: 15 Jul 1996 09:06:57 -0500 Organization: Des Moines Area Community College Lines: 311 Message-ID: <4sdja1$4rf@infoborg.dmacc.cc.ia.us> References: <4s3o4k$m5u@news.sei.cmu.edu> Reply-To: "Charles F. Randall" <crandall@dmacc.cc.ia.us> NNTP-Posting-Host: infoborg.dmacc.cc.ia.us Keywords: security CERT This was posted to comp.security.announce. Are these patches already applied to 2.1.5R? -Randy CERT Bulletin <cert-advisory-request@cert.org> wrote: -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= CERT(sm) Vendor-Initiated Bulletin VB-96.11 July 11, 1996 Topic: security compromise from ppp Source: FreeBSD, Inc. To aid in the wide distribution of essential security information, the CERT Coordination Center is forwarding the following information from FreeBSD, Inc. FreeBSD urges you to act on this information as soon as possible. FreeBSD contact information is included in the forwarded text below; please contact them if you have any questions or need further information. =======================FORWARDED TEXT STARTS HERE============================ ============================================================================= FreeBSD-SA-96:15 Security Advisory FreeBSD, Inc. Topic: security compromise from ppp Category: core Module: ppp Announced: 1996-07-04 Affects: FreeBSD 2.0.5, 2.1, 2.1-stable, and 2.2-current Corrected: 2.1-stable and 2.2-current as of 1996-06-10 FreeBSD only: unknown Patches: ftp://freebsd.org/pub/CERT/patches/SA-96:15/ ============================================================================= I. Background FreeBSD ships a userland ppp program that can be used by users to set up ppp connections. This program is also known as ijppp. The ppp program has a vulnerability that allows any user to run commands under root privileges. II. Problem Description The ppp program does not properly manage user privileges, allowing users to run any program with root privileges. III. Impact This vulnerability can only be exploited by users with a valid account on the local system to easily obtain superuser access. IV. Workaround One may simply disable the setuid bit on all copies of the ppp program. This will close the vulnerability but will only allow the superuser to set up ppp connections. As root, execute the commands: # chmod 555 /usr/sbin/ppp then verify that the setuid permissions of the files have been removed. The permissions array should read "-r-xr-xr-x" as shown here: # ls -l /usr/sbin/ppp -r-xr-xr-x 1 root bin 86016 Nov 16 1995 /usr/sbin/ppp V. Solution Patches are available which eliminate this vulnerability. The following patch should be applied to the system sources and ppp should be rebuilt and reinstalled. The first patch is against the FreeBSD 2.1 and FreeBSD-stable source tree. The second patch is for FreeBSD-current (version before 1996-06-10). Apply the patch, then (being superuser): # cd /usr/src/usr.sbin/ppp # make depend # make all # make install Index: command.c =================================================================== RCS file: /home/ncvs/src/usr.sbin/ppp/command.c,v retrieving revision 1.5.4.3 retrieving revision 1.5.4.4 diff -u -r1.5.4.3 -r1.5.4.4 --- command.c 1996/02/05 17:02:52 1.5.4.3 +++ command.c 1996/06/10 09:41:49 1.5.4.4 @@ -17,7 +17,7 @@ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. * - * $Id: command.c,v 1.5.4.3 1996/02/05 17:02:52 dfr Exp $ + * $Id: command.c,v 1.5.4.4 1996/06/10 09:41:49 ache Exp $ * */ #include <sys/types.h> @@ -187,9 +187,14 @@ * We are running setuid, we should change to * real user for avoiding security problems. */ - setgid( getgid() ); - setuid( getuid() ); - + if (setgid(getgid()) < 0) { + perror("setgid"); + exit(1); + } + if (setuid(getuid()) < 0) { + perror("setuid"); + exit(1); + } TtyOldMode(); if(argc > 0) execvp(argv[0], argv); Index: chat.c =================================================================== RCS file: /home/ncvs/src/usr.sbin/ppp/chat.c,v retrieving revision 1.4.4.1 retrieving revision 1.4.4.2 diff -u -r1.4.4.1 -r1.4.4.2 --- chat.c 1995/10/06 11:24:31 1.4.4.1 +++ chat.c 1996/06/10 09:41:45 1.4.4.2 @@ -18,7 +18,7 @@ * Columbus, OH 43221 * (614)451-1883 * - * $Id: chat.c,v 1.4.4.1 1995/10/06 11:24:31 davidg Exp $ + * $Id: chat.c,v 1.4.4.2 1996/06/10 09:41:45 ache Exp $ * * TODO: * o Support more UUCP compatible control sequences. @@ -331,6 +331,15 @@ nb = open("/dev/tty", O_RDWR); dup2(nb, 0); LogPrintf(LOG_CHAT, "exec: %s\n", command); + /* switch back to original privileges */ + if (setgid(getgid()) < 0) { + LogPrintf(LOG_CHAT, "setgid: %s\n", strerror(errno)); + exit(1); + } + if (setuid(getuid()) < 0) { + LogPrintf(LOG_CHAT, "setuid: %s\n", strerror(errno)); + exit(1); + } pid = execvp(command, vector); LogPrintf(LOG_CHAT, "execvp failed for (%d/%d): %s\n", pid, errno, command); exit(127); Patch for FreeBSd-current before 1996-06-10: Index: command.c =================================================================== RCS file: /home/ncvs/src/usr.sbin/ppp/command.c,v retrieving revision 1.17 retrieving revision 1.18 diff -u -r1.17 -r1.18 --- command.c 1996/05/11 20:48:22 1.17 +++ command.c 1996/06/09 20:40:58 1.18 @@ -17,7 +17,7 @@ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. * - * $Id: command.c,v 1.17 1996/05/11 20:48:22 phk Exp $ + * $Id: command.c,v 1.18 1996/06/09 20:40:58 ache Exp $ * */ #include <sys/types.h> @@ -190,9 +190,14 @@ * We are running setuid, we should change to * real user for avoiding security problems. */ - setgid( getgid() ); - setuid( getuid() ); - + if (setgid(getgid()) < 0) { + perror("setgid"); + exit(1); + } + if (setuid(getuid()) < 0) { + perror("setuid"); + exit(1); + } TtyOldMode(); if(argc > 0) execvp(argv[0], argv); Index: chat.c =================================================================== RCS file: /home/ncvs/src/usr.sbin/ppp/chat.c,v retrieving revision 1.10 retrieving revision 1.11 diff -u -r1.10 -r1.11 --- chat.c 1996/05/11 20:48:20 1.10 +++ chat.c 1996/06/09 20:40:56 1.11 @@ -18,7 +18,7 @@ * Columbus, OH 43221 * (614)451-1883 * - * $Id: chat.c,v 1.10 1996/05/11 20:48:20 phk Exp $ + * $Id: chat.c,v 1.11 1996/06/09 20:40:56 ache Exp $ * * TODO: * o Support more UUCP compatible control sequences. @@ -393,6 +393,15 @@ nb = open("/dev/tty", O_RDWR); dup2(nb, 0); LogPrintf(LOG_CHAT_BIT, "exec: %s\n", command); + /* switch back to original privileges */ + if (setgid(getgid()) < 0) { + LogPrintf(LOG_CHAT_BIT, "setgid: %s\n", strerror(errno)); + exit(1); + } + if (setuid(getuid()) < 0) { + LogPrintf(LOG_CHAT_BIT, "setuid: %s\n", strerror(errno)); + exit(1); + } pid = execvp(command, vector); LogPrintf(LOG_CHAT_BIT, "execvp failed for (%d/%d): %s\n", pid, errno, command); exit(127); ============================================================================= FreeBSD, Inc. Web Site: http://www.freebsd.org/ Confidential contacts: security-officer@freebsd.org PGP Key: ftp://freebsd.org/pub/CERT/public_key.asc Security notifications: security-notifications@freebsd.org Security public discussion: security@freebsd.org Notice: Any patches in this document may not apply cleanly due to modifications caused by digital signature or mailer software. Please reference the URL listed at the top of this document for original copies of all patches if necessary. ============================================================================= ========================FORWARDED TEXT ENDS HERE============================= If you believe that your system has been compromised, contact the CERT Coordination Center or your representative in the Forum of Incident Response and Security Teams (FIRST). We strongly urge you to encrypt any sensitive information you send by email. The CERT Coordination Center can support a shared DES key and PGP. Contact the CERT staff for more information. Location of CERT PGP key ftp://info.cert.org/pub/CERT_PGP.key CERT Contact Information - ------------------------ Email cert@cert.org Phone +1 412-268-7090 (24-hour hotline) CERT personnel answer 8:30-5:00 p.m. EST (GMT-5)/EDT(GMT-4), and are on call for emergencies during other hours. Fax +1 412-268-6989 Postal address CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 USA CERT publications, information about FIRST representatives, and other security-related information are available from http://www.cert.org/ ftp://info.cert.org/pub/ CERT advisories and bulletins are also posted on the USENET newsgroup comp.security.announce To be added to our mailing list for CERT advisories and bulletins, send your email address to cert-advisory-request@cert.org CERT is a service mark of Carnegie Mellon University. This file: ftp://info.cert.org/pub/cert_bulletins/VB-96.11.freebsd -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMeURZXVP+x0t4w7BAQHIygP/Sz+ie128GTqeIObCcPbZs0CV3NHQ/Klw KQNam2c+6mcodw16xTjAXO8geV5wSANV074d7UXnlzSQN69QKhHzXcBIY2cQptWd AlXgChaipTriyU3WupKUvD7rwkjG/uTfcymiWDrqs4UhT2AFwKUUZEzldrHqxd2c fjp/rTgO9b8= =nWXf -----END PGP SIGNATURE----- -- Charles F. Randall E-mail: crandall@dmacc.cc.ia.us UNIX Systems Programmer Voice: (515) 965-7057 Perl Hacker - Powered by FreeBSD! FAX: (515) 965-7305