Bug Id
6763320

Product
Solaris 10 Operating System
OpenSolaris

Date of Resolved Release
09-Mar-2009

A Security Vulnerability in the Solaris NFS Daemon (nfsd(1M)) May Allow Unauthorized Access to Data

1. Impact

A security vulnerability in the Solaris NFS server (nfsd(1M)) may grant multiple security modes to certain NFSv3 remote clients and thereby allow remote unprivileged users on those clients to gain unauthorized access to shared files.

Sun acknowledges with thanks Daniel Van Derveer, for discovering and reporting this issue.

2. Contributing Factors

This issue can occur in the following releases:

SPARC Platform

• Solaris 10 without patch 139462-02
• OpenSolaris based upon builds snv_01 through snv_105

x86 Platform

• Solaris 10 without patch 139463-02
• OpenSolaris based upon builds snv_01 through snv_105

Notes:

1. Solaris 8 and 9 are not impacted by this issue.

2. OpenSolaris distributions may include additional bug fixes above and beyond the build from which it was derived. The base build can be derived as follows:

$ uname -v
snv_86 

3. Only NFS servers that support NFSv3 and multiple security modes are vulnerable to this issue.  Servers that only support NFSv4 or NFSv3 with a single security mode are not vulnerable.

To determine if a system allows NFSv3 and is potentially vulnerable, the following command can be run:

$ grep NFS_SERVER_VERSMIN /etc/default/nfs
#NFS_SERVER_VERSMIN=2

If the value of 'NFS_SERVER_VERSMIN' is less than '4', then the server is configured to use NFSv3 and may be vulnerable to this issue.

4. The NFS server (nfsd(1M)) must be configured to support multiple security modes (see share_nfs(1M)).  This can be determined by running the following command:

$ share -F nfs 
-@pool/builds   /builds/clones   sec=sys,rw=testhost,sec=krb5,rw   ""  

The reporting of at least two different "sec=" options in the output indicates that the system is configured to support multiple security modes.

3. Symptoms

There are no predictable symptoms that would indicate the described issue has occurred.

4. Workaround

To work around this issue, there are two options:

A) Use the same access list for all security modes supported by the NFS server.

or:

B) Allow only NFSv4 traffic to the server by editing /etc/default/nfs (see nfs(4)) and change 'NFS_SERVER_VERSMIN' to '4':


And then restart the nfs server using the following command:

$ svcadm restart svc:/network/nfs/server

5. Resolution

SPARC Platform

• Solaris 10 with patch 139462-02 or later
• OpenSolaris based upon builds snv_106 or later

x86 Platform

• Solaris 10 with patch 139463-02 or later
• OpenSolaris based upon builds snv_106 or later

For more information on Security Sun Alerts, see 1009886.1.

This Sun Alert notification is being provided to you on an "AS IS" basis. This Sun Alert notification may contain information provided by third parties. The issues described in this Sun Alert notification may or may not impact your system(s). Sun makes no representations, warranties, or guarantees as to the information contained herein. ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN. This Sun Alert notification contains Sun proprietary and confidential information. It is being provided to you pursuant to the provisions of your agreement to purchase services from Sun, or, if you do not have such an agreement, the Sun.com Terms of Use. This Sun Alert notification may only be used for the purposes contemplated by these agreements.

Copyright 2000-2009 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, CA 95054 U.S.A. All rights reserved.

References

139462-02
139463-02





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