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FreeBSD-SA-01:45                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          samba

Category:       ports
Module:         samba
Announced:      2001-07-10
Credits:        Michal Zalewski <lcamtuf@bos.bindview.com>
Affects:        Ports collection prior to the correction date.
Corrected:      2001-06-23
Vendor status:  Updated version released
FreeBSD only:   NO

I.   Background

Samba is an implementation of the Server Message Block (SMB)
protocol.

II.  Problem Description

The samba ports, versions prior to samba-2.0.10,
samba-devel-2.2.0a, and ja-samba-2.0.9.j1.0_1, fail to properly
validate NetBIOS names.  By sending a specially crafted NetBIOS name
containing unix path characters, a remote user may be able to cause
the samba server to write the log files to arbitrary locations on
the local filesystems.

If samba is configured to use the '%m' macro in the 'log file'
directive, the NetBIOS name will be substituted without sanity
checking.  This will allow the remote user to insert arbitrary paths
given the 15 character NetBIOS name limit.  However, if a local user
can create symlinks accessible via this problem, a remote user may be
able to append to any arbitrary file or filesystem.

The samba port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains over 5400 third-party applications in a ready-to-install
format. The ports collection shipped with FreeBSD 4.3 is vulnerable
to this problem since it was discovered after its release.

FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.

III. Impact

Remote users using specially crafted NetBIOS names may be able to
insert arbitrary paths in log file names, causing log files to be
written in unintended and inappropriate locations.

If a local user can create symlinks accessible via this problem, a
remote user may be able to append to any arbitrary file or
filesystem.

If you have not chosen to install the samba port/package, then
your system is not vulnerable to this problem.

IV.  Workaround

Remove all occurrences of the %m macro from smb.conf.  Replacing the %m
macro with the %I macro (replaced with the IP address of the client machine)
is the recommended workaround for most sites.

V.   Solution

One of the following:

1) Upgrade your entire ports collection and rebuild the samba port.

2) Deinstall the old package and install a new package dated after the
correction date, obtained from the following directories:

[i386]
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/net/samba-2.0.10.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/net/samba-2.0.10.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/net/samba-2.2.0a.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/net/samba-2.2.0a.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/japanese/ja-samba-2.0.9.j1.0_1.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/japanese/ja-samba-2.0.9.j1.0_1.tgz

[alpha]
Packages are not automatically generated for the alpha architecture at
this time due to lack of build resources.

3) download a new port skeleton for the samba port from:

http://www.freebsd.org/ports/

and use it to rebuild the port.

4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz

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