AusCERT - ESB-2006.0378 -- [UNIX/Linux][FreeBSD] -- Inoperative access controls in ypserv(8)

HOME
About AusCERT
Membership
PKI Services
Training
Publications
Sec. Bulletins
Conferences
News & Media
Services
Web Log
Site Map
Site Help
Member login
ESB-2006.0378 -- [UNIX/Linux][FreeBSD] -- Inoperative access controls in ypserv(8)
Date: 01 June 2006

Click here for printable version
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

===========================================================================
             AUSCERT External Security Bulletin Redistribution

                  ESB-2006.0378 -- [UNIX/Linux][FreeBSD]
                 Inoperative access controls in ypserv(8)
                                1 June 2006

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              ypserv
Publisher:            FreeBSD
Operating System:     FreeBSD 6
                      FreeBSD 5
                      UNIX variants (UNIX, Linux, OSX)
Impact:               Inappropriate Access
Access:               Remote/Unauthenticated
CVE Names:            CVE-2006-2655

Original Bulletin:
   ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:15.ypserv.asc

Comment: This advisory references vulnerabilities in products which run on
         platforms other than FreeBSD. It is recommended that administrators
         running ypserv check for an updated version of the software for
         their operating system.

- --------------------------BEGIN INCLUDED TEXT--------------------

- -----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
<URL:http://www.freebsd.org/security/>.

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-----

- --------------------------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.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:

        http://www.auscert.org.au/render.html?it=3192

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

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 member emergencies only.
===========================================================================

-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967

iQCVAwUBRH5Zyyh9+71yA2DNAQKDcwP+I7Lk8u5gCThSXbltYaehPyLLXKhxZ/p7
cv/cAuBEzkYHHIYc2v2l5mUXMcDzpKFBbrd09L+10zPHMYFP9Ova7+Ztitskx5mT
7h03SOsg1wr3phuyPgf8raVhKZfk2S0vyKFYPnrVIm3L/smqcQOBphyqeqdtqL86
0y3rU8zvDe4=
=gQNN
-----END PGP SIGNATURE-----