From owner-freebsd-security-notifications@FreeBSD.ORG Tue Feb 4 10:33:05 2003 Return-Path: Received: from mx2.freebsd.org([216.136.204.119]) (6711 bytes) by packetstormsecurity.org via smail with P:esmtp/D:user/T:local (sender: ) id for ; Tue, 4 Feb 2003 10:33:05 -0800 (PST) (Smail-3.2.0.111 2000-Feb-17 #9 built 2000-Apr-13) Received: from hub.freebsd.org (hub.freebsd.org [216.136.204.18]) by mx2.freebsd.org (Postfix) with ESMTP id BABAB56072; Tue, 4 Feb 2003 10:46:45 -0800 (PST) (envelope-from owner-freebsd-security-notifications@FreeBSD.ORG) Received: by hub.freebsd.org (Postfix, from userid 538) id 528D337B401; Tue, 4 Feb 2003 10:46:39 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by hub.freebsd.org (Postfix) with SMTP id 857372E801D; Tue, 4 Feb 2003 10:46:38 -0800 (PST) Received: by hub.freebsd.org (bulk_mailer v1.12); Tue, 4 Feb 2003 10:46:38 -0800 Delivered-To: freebsd-security-notifications@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8174237B407; Tue, 4 Feb 2003 10:46:37 -0800 (PST) Received: from freefall.freebsd.org (freefall.freebsd.org [216.136.204.21]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8175143FB1; Tue, 4 Feb 2003 10:46:34 -0800 (PST) (envelope-from security-advisories@freebsd.org) Received: from freefall.freebsd.org (nectar@localhost [127.0.0.1]) by freefall.freebsd.org (8.12.6/8.12.6) with ESMTP id h14IkYNS050806; Tue, 4 Feb 2003 10:46:34 -0800 (PST) (envelope-from security-advisories@freebsd.org) Received: (from nectar@localhost) by freefall.freebsd.org (8.12.6/8.12.6/Submit) id h14IkYtj050805; Tue, 4 Feb 2003 10:46:34 -0800 (PST) Date: Tue, 4 Feb 2003 10:46:34 -0800 (PST) Message-Id: <200302041846.h14IkYtj050805@freefall.freebsd.org> X-Authentication-Warning: freefall.freebsd.org: nectar set sender to security-advisories@freebsd.org using -f From: FreeBSD Security Advisories To: FreeBSD Security Advisories Subject: FreeBSD Security Advisory FreeBSD-SA-03:01.cvs Sender: owner-freebsd-security-notifications@FreeBSD.ORG List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: Reply-To: postmaster@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Status: RO Content-Length: 4231 Lines: 113 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-03:01.cvs Security Advisory The FreeBSD Project Topic: remotely exploitable vulnerability in cvs server Category: contrib Module: contrib_cvs Announced: 2003-02-04 Credits: Stefan Esser Affects: All FreeBSD versions prior to 4.6-RELEASE-p7, 4.7-RELEASE-p4, 5.0-RELEASE-p1 Corrected: 2003-01-21 22:26:46 UTC (RELENG_4) 2003-02-04 18:05:07 UTC (RELENG_5_0) 2003-02-04 18:07:20 UTC (RELENG_4_7) 2003-02-04 18:08:26 UTC (RELENG_4_6) FreeBSD only: NO I. Background The Concurrent Versions System (CVS) is a version control system. It may be used to access a repository locally, or to access a `remote repository' using several different methods, including `ext' (rsh), and `pserver' (password-authenticated server). When accessing a remote repository, the target machine runs the CVS server to fulfill client requests. II. Problem Description The implementation of the CVS server contains a programming error which can lead to a block of memory being freed more than once (i.e. a double-free bug). Separately, the CVS server allows clients with write access to specify arbitrary commands to execute as part of an update (update-prog) or commit (checkin-prog). This is a dangerous feature that is generally not needed: there are other, safer methods of triggering program execution. III. Impact An attacker may exploit the double-free bug in order to bypass write access checks. Combined with the update-prog/checkin-prog feature, the attacker may be able to execute arbitrary commands with the privileges of the CVS server. The impact is most severe when running the CVS server in `pserver' mode to provide read-only access to the world (anoncvs). IV. Workaround Do not use `pserver' mode directly. Instead, use one of the safer methods described in the following online resources: V. Solution 1) Upgrade your vulnerable system to 4.7-STABLE; or to the RELENG_4_7 (4.7-RELEASE-p4), RELENG_4_6 (4.6-RELEASE-p7), or RELENG_5_0 (5.0-RELEASE-p1) security branch dated after the correction date. 2) To patch your present system: The following patch has been verified to apply to FreeBSD 4.6, 4.7, and 5.0 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:01/cvs.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:01/cvs.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch # cd /usr/src/gnu/usr.bin/cvs # make obj && make depend && make && make install VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Path Revision Branch - ------------------------------------------------------------------------- src/contrib/cvs/src/server.c RELENG_5_0 1.17.2.1 RELENG_4_7 1.13.2.2.6.1 RELENG_4_6 1.13.2.2.4.1 - ------------------------------------------------------------------------- VII. References -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (FreeBSD) iD8DBQE+QAU9FdaIBMps37IRAvYzAKCeaZ1eWwiWNxRqgNRwnn4TwuwPPACdGF8T 0Ym2kCQxU0sJSRxmgAA/yM4= =9+5m -----END PGP SIGNATURE----- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security-notifications" in the body of the message