[200404-21]Multiple Vulnerabilities in Samba

[pahud]

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Gentoo Linux Security Advisory GLSA 200404-21
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
http://security.gentoo.org/
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severity: Normal
Title: Multiple Vulnerabilities in Samba
Date: April 29, 2004
Bugs: #41800, #45965
ID: 200404-21

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Synopsis
========

There is a bug in smbfs which may allow local users to gain root via a
setuid file on a mounted Samba share. Also, there is a tmpfile symlink
vulnerability in the smbprint script distributed with Samba.

Background
==========

Samba is a package which allows UNIX systems to act as file servers for
Windows computers. It also allows UNIX systems to mount shares exported
by a Samba/CIFS/Windows server. smbmount is a program in the Samba
package which allows normal users on a UNIX system to mount remote
shares. smbprint is an example script included in the Samba package
which can be used to facilitate network printing.

Affected packages
=================

-------------------------------------------------------------------
Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 net-fs/samba <= 3.0.2a >= 3.0.2a-r2

Description
===========

Two vulnerabilities have been discovered in Samba. The first
vulnerability allows a local user who has access to the smbmount
command to gain root. An attacker could place a setuid-root binary on a
Samba share/server he or she controls, and then use the smbmount
command to mount the share on the target UNIX box. The remote Samba
server must support UNIX extensions for this to work. This has been
fixed in version 3.0.2a.

The second vulnerability is in the smbprint script. By creating a
symlink from /tmp/smbprint.log, an attacker could cause the smbprint
script to write to an arbitrary file on the system. This has been fixed
in version 3.0.2a-r2.

Impact
======

Local users with access to the smbmount command may gain root access.
Also, arbitrary files may be overwritten using the smbprint script.

Workaround
==========

To workaround the setuid bug, remove the setuid bits from the
/usr/bin/smbmnt, /usr/bin/smbumount and /usr/bin/mount.cifs binaries.
However, please note that this workaround will prevent ordinary users
from mounting remote SMB and CIFS shares.

To work around the smbprint vulnerability, set "debug=no" in the
smbprint configuration.

Resolution
==========

All users should update to the latest version of the Samba package.

The following commands will perform the upgrade:

# emerge sync

# emerge -pv ">=net-fs/samba-3.0.2a-r2"
# emerge ">=net-fs/samba-3.0.2a-r2"

Those who are using Samba's password database also need to run the
following command:

# pdbedit --force-initialized-passwords

Those using LDAP for Samba passwords also need to check the
sambaPwdLastSet attribute on each account, and ensure it is not 0.

References
==========

[ 1 ] BugTraq Thread: Samba 3.x + kernel 2.6.x local root vulnerability
http://www.securityfocus.com/archive/1/ ... 04-04-15/1
[ 2 ] BugTraq: smbprint Vulnerability
http://seclists.org/lists/bugtraq/2004/Mar/0189.html

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

http://security.gentoo.org/glsa/glsa-200404-21.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2004 Gentoo Technologies, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/1.0