Bug Id
6848431

Product
Solaris 10 Operating System
OpenSolaris

Date of Resolved Release
14-Oct-2009

A Security Vulnerability in the ZFS Filesystem May Allow An Unprivileged User to Take Ownership of Files Belonging to Another User

1. Impact

A security vulnerability in the ZFS file system in OpenSolaris and Solaris 10 systems with patches 137137-09 (SPARC) or 137138-09 (x86) installed may allow a local unprivileged user with the 'file_chown_self' privilege to take ownership of files belonging to another user.

2. Contributing Factors

This issue can occur in the following releases:

SPARC Platform

• Solaris 10 with patch 137137-09 and without patch 141444-09
• OpenSolaris based upon builds snv_100 through snv_117

x86 Platform

• Solaris 10 with patch 137138-09 and without patch 141445-09
• OpenSolaris based upon builds snv_100 through snv_117

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. This issue only affects systems with ZFS file systems where local users have been granted the {PRIV_FILE_CHOWN_SELF} (see chown(2)) privilege which allows them to modify ownership of files where the ownership matches the user's current effective user ID. If the default operating system configuration option '{_POSIX_CHOWN_RESTRICTED}' has been disabled then the 'file_chown_self' privilege is asserted in the inheritable set of all processes unless overridden by policy.conf(4) or user_attr(4).

To determine if a system is using ZFS, the following command can be run:

$ zfs list

If there are any pools listed, then ZFS is being used.

To determine if a user has been given the privilege to give away ownership of a file, the following command can be run:

$ ppriv <pid> | grep "file_chown_self" || echo "User not authorized give away ownership of files"
E: basic,dtrace_kernel,dtrace_proc,dtrace_user,file_chown_self,proc_owner
I: basic,dtrace_kernel,dtrace_proc,dtrace_user,file_chown_self,proc_owner
P: basic,dtrace_kernel,dtrace_proc,dtrace_user,file_chown_self,proc_owner

and then check if the output lists 'file_chown_self'.

To determine if all users system wide have been given the privilege to give away ownership of a file, the following command can be run:

$ grep "set rstchown=0" /etc/system && echo "All users have privilege to give away ownership of a file"
All users have privilege to give away ownership of a file

3. Symptoms

There are no predictable symptoms that would indicate the described vulnerability has been exploited.

4. Workaround

There is no workaround for this issue. Please see the Resolution section below.

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

• Solaris 10 with patch 141444-09 or later
• OpenSolaris based upon builds snv_118 or later

x86 Platform

• Solaris 10 with patch 141445-09 or later
• OpenSolaris based upon builds snv_118 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.

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References

141444-09
141445-09





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