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CA-91:21                     CERT Advisory
                            December 6, 1991
		  SunOS NFS Jumbo and fsirand Patches

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The Computer Emergency Response Team/Coordination Center (CERT/CC)
has received information concerning several vulnerabilities in Sun
Microsystems, Inc. (Sun) Network File System (NFS) and the fsirand
program. These vulnerabilities affect SunOS versions 4.1.1, 4.1, and
4.0.3 on all architectures.

Sun has provided separate patches for these vulnerabilities for SunOS
4.1.1, and has provided an initial patch for SunOS 4.1.  Sun will be
providing complete patches for 4.1 and 4.0.3 at a later date.  On
SunOS 4.1.1 systems, Sun states that patch 100173-07 must be installed
before patch 100424-1.  The patches are available through your local
Sun Answer Centers worldwide as well as through anonymous ftp from the
ftp.uu.net (192.48.96.2) system in the /sun-dist directory.

Fix                        PatchID        Filename            Checksum
NFS Jumbo 4.1.1            100173-07      100173-07.tar.Z     07044   209
NFS Jumbo 4.1              100121-08      100121-08.tar.Z     61464   287
fsirand 4.1.1              100424-01      100424-01.tar.Z     63070    50

Please note that Sun will occasionally update patch files.  If you
find that the checksum is different please contact Sun or the CERT/CC
for verification.

Sun recommends that sites upgrade to SunOS 4.1.1 to benefit from the
security improvements.  In addition, they recommend the installation
of all security-related patches applicable to the version of SunOS
that you are running.

A general NFS security note: due to security flaws in the protocol,
the CERT/CC recommends filtering SunRPC and NFS IP packets (sockets
111 and 2049) between the local network and the Internet.  This will
prevent intruders outside your local network from accessing your
files.

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NFS Jumbo Patch, SunOS 4.1.1

I.   Description

This patch fixes several SunOS NFS bugs (not all security-related).
The patch file, 100173-07.tar.Z, contains fixes for SunOS version
4.1.1.  The BugIDs fixed in this patch are:

1039977 1032959 1029628 1037476 1038302 1034328 1045536 1030884 1045993
1047557 1052330 1053679 1041409 1065361 1066287 1064433 1070654

See the README file provided with the patch for more information.
 
II.  Impact

These vulnerabilities (and bugs) have multiple impacts, including
crashing the system, allowing unauthorized system access, and causing
a problem with file group ownership.

III. Solution

Obtain the patch from Sun or from ftp.uu.net and install, following
the provided instructions, with the following exception:

line 112 of the README file currently reads:

    mv /sys/`arch -k`/OBJ/nfs_subr.o /sys/arch -k`/OBJ/nfs_subr.o.FCS
                                          ^^^^^^^^
it should read:

    mv /sys/`arch -k`/OBJ/nfs_subr.o /sys/`arch -k`/OBJ/nfs_subr.o.FCS
                                          ^^^^^^^^^
(Note the one-character difference.)
        
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NFS Jumbo Patch, SunOS 4.1

I.   Description

This patch fixes several SunOS NFS bugs (not all security-related).
The patch file, 100121-08.tar.Z, contains fixes for SunOS version 4.1.
The BugIDs fixed in this patch are:

1026933 1034007 1039977 1029628 1037476 1038327 1038302
1034328 1045536 1045993 1047557 1030884 1052330 1053679

See the README file provided with the patch for more information.
 
II.  Impact

These vulnerabilities (and bugs) have multiple impacts, including
crashing the system, allowing unauthorized system access, and causing
a problem with file group ownership.

III. Solution

Obtain the patch from Sun or from ftp.uu.net and install, following
the provided instructions.
        
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fsirand, SunOS 4.1.1

I.   Description

A security vulnerability exists in SunOS NFS relating to the way in
which it allocates file handles.  The patch file, 100424-01.tar.Z,
contains a fix for SunOS version 4.1.1.  The BugID fixed in this patch
is 1063470.

II.  Impact

The fsirand program could allow a remote system user to guess NFS file
handles, thereby potentially allowing them to mount and access your
NFS file systems.

III. Solution 
        
Obtain the patch from Sun or from ftp.uu.net and install, following
the provided instructions.  You must install PatchID 100173-07 before
installing this patch.

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The CERT/CC wishes to thank Bob Drzyzgula of the Federal Reserve Board,
Leendert van Doorn of Vrije University, and Wietse Venema of Eindhoven
University for their assistance.
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If you believe that your system has been compromised, contact CERT/CC via
telephone or e-mail.

Internet E-mail: cert@cert.org
Telephone: 412-268-7090 24-hour hotline:
           CERT/CC personnel answer 7:30a.m.-6:00p.m. EST(GMT-5)/EDT(GMT-4),
           on call for emergencies during other hours.

Computer Emergency Response Team/Coordination Center (CERT/CC)
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890

Past advisories and other information related to computer security are
available for anonymous ftp from the cert.org (192.88.209.5)
system.


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