-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-06:15.ypserv Security Advisory The FreeBSD Project Topic: Inoperative access controls in ypserv(8) Category: core Module: ypserv Announced: 2006-05-31 Credits: Hokan Affects: All FreeBSD 5.x and FreeBSD 6.x releases Corrected: 2006-05-31 22:31:21 UTC (RELENG_6, 6.1-STABLE) 2006-05-31 22:31:42 UTC (RELENG_6_1, 6.1-RELEASE-p1) 2006-05-31 22:32:04 UTC (RELENG_6_0, 6.0-RELEASE-p8) 2006-05-31 22:32:22 UTC (RELENG_5, 5.5-STABLE) 2006-05-31 22:32:49 UTC (RELENG_5_5, 5.5-RELEASE-p1) 2006-05-31 22:33:17 UTC (RELENG_5_4, 5.4-RELEASE-p15) 2006-05-31 22:33:41 UTC (RELENG_5_3, 5.3-RELEASE-p30) CVE Name: CVE-2006-2655 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background The ypserv(8) utility is a server which distributes NIS databases to client systems within an NIS domain. II. Problem Description There are two documented methods of restricting access to NIS maps through ypserv(8): through the use of the /var/yp/securenets file, and through the /etc/hosts.allow file. While both mechanisms are implemented in the server, a change in the build process caused the "securenets" access restrictions to be inadvertantly disabled. III. Impact ypserv(8) will not load or process any of the networks or hosts specified in the /var/yp/securenets file, rendering those access controls ineffective. IV. Workaround One possible workaround is to use /etc/hosts.allow for access control, as shown by examples in that file. Another workaround is to use a firewall (e.g., ipfw(4), ipf(4), or pf(4)) to limit access to RPC functions from untrusted systems or networks, but due to the complexities of RPC, it might be difficult to create a set of firewall rules which accomplish this without blocking all access to the machine in question. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 5-STABLE or 6-STABLE, or to the RELENG_6_1, RELENG_6_0, RELENG_5_5, RELENG_5_4, or RELENG_5_3 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 5.3, 5.4, 5.5, 6.0, and 6.1 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch http://security.FreeBSD.org/patches/SA-06:15/ypserv.patch # fetch http://security.FreeBSD.org/patches/SA-06:15/ypserv.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch # cd /usr/src/usr.sbin/ypserv # 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. Branch Revision Path - ------------------------------------------------------------------------- RELENG_5 src/usr.sbin/ypserv/yp_access.c 1.22.6.1 RELENG_5_5 src/UPDATING 1.342.2.35.2.1 src/sys/conf/newvers.sh 1.62.2.21.2.3 src/usr.sbin/ypserv/yp_access.c 1.22.18.1 RELENG_5_4 src/UPDATING 1.342.2.24.2.24 src/sys/conf/newvers.sh 1.62.2.18.2.20 src/usr.sbin/ypserv/yp_access.c 1.22.10.1 RELENG_5_3 src/UPDATING 1.342.2.13.2.33 src/sys/conf/newvers.sh 1.62.2.15.2.35 src/usr.sbin/ypserv/yp_access.c 1.22.8.1 RELENG_6 src/usr.sbin/ypserv/yp_access.c 1.22.12.1 RELENG_6_1 src/UPDATING 1.416.2.22.2.3 src/sys/conf/newvers.sh 1.69.2.11.2.3 src/usr.sbin/ypserv/yp_access.c 1.22.16.1 RELENG_6_0 src/UPDATING 1.416.2.3.2.13 src/sys/conf/newvers.sh 1.69.2.8.2.9 src/usr.sbin/ypserv/yp_access.c 1.22.14.1 - ------------------------------------------------------------------------- VII. References http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2655 The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-06:15.ypserv.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFEfhuUFdaIBMps37IRAhH5AJ9cpTLcR+aWSRPUa1zUDYThhKDqowCggYr1 4OyjFHW/C+NB9nMIX8Wf7IE= =NNUN -----END PGP SIGNATURE-----