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AUSCERT External Security Bulletin Redistribution
ESB-2001.172 -- FreeBSD-SA-01:36.samba
samba ports contain locally exploitable /tmp races
30 April 2001
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AusCERT Security Bulletin Summary
---------------------------------
Product: samba
Vendor: FreeBSD Ports Collection
Operating System: FreeBSD
BSD
Linux
Unix
Platform: Alpha
i386
Impact: Modify Arbitrary Files
Increased Privileges
Access Required: Existing Account
Ref: ESB-2001.156
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FreeBSD-SA-01:36 Security Advisory
FreeBSD, Inc.
Topic: samba ports contain locally exploitable /tmp races
Category: ports
Module: samba
Announced: 2001-04-23
Credits: Marcus Meissner <Marcus.Meissner@caldera.de>
Affects: Ports collection prior to the correction date.
Corrected: 2001-04-18
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-2.0.8 and samba-devel-2.2.0,
contain /tmp races that may allow local users to cause arbitrary
files and devices to be overwritten. Due to easily predictable
printer queue cache file names, local users may create symbolic links
to any file or device causing it to be corrupted when a remote user
accesses a printer. In addition, the file will be left with world-
writable permission allowing any user to enter their own data.
The samba ports are not installed by default, nor are they "part of
FreeBSD" as such: they are part of the FreeBSD ports collection, which
contains over 5000 third-party applications in a ready-to-install
format. The ports collections shipped with FreeBSD 3.5.1 and 4.2
contain this problem since it was discovered after the releases.
The ports collection that shipped with FreeBSD 4.3 is not vulnerable
since this problem was corrected prior to the 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
Unprivileged local users may cause arbitrary files or devices to be
corrupted and gain increased privileges on the local system.
If you have not chosen to install the samba ports/packages, then
your system is not vulnerable to this problem.
Samba servers that do not have any printers configured are not
vulnerable.
IV. Workaround
Deinstall the samba port/package, if you have installed it.
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:
[i386]
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/net/samba-2.0.8.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/net/samba-2.0.8.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/net/samba-devel-2.2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/net/samba-devel-2.2.0.tgz
NOTE: it may be several days before updated packages are available.
[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 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-3-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz
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