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AUSCERT External Security Bulletin Redistribution
ESB-2000.239 -- FreeBSD-SA-00:45
esound port allows file permissions to be modified
1 September 2000
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AusCERT Security Bulletin Summary
---------------------------------
Product: esound
Vendor: FreeBSD Ports Collection
Operating System: FreeBSD
Linux
Unix
Platform: N/A
Impact: Increased Privileges
Access Required: Local
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FreeBSD-SA-00:45 Security Advisory
FreeBSD, Inc.
Topic: esound port allows file permissions to be modified
Category: ports
Module: esound
Announced: 2000-08-31
Credits: Brian Feldman <green@FreeBSD.org> during internal auditing
Affects: Ports collection prior to the correction date
Corrected: 2000-06-30
Vendor status: Contacted
FreeBSD only: NO
I. Background
EsounD is a component of the GNOME desktop environment which is
responsible for multiplexing access to audio devices.
II. Problem Description
The esound port, versions 0.2.19 and earlier, creates a world-writable
directory in /tmp owned by the user running the EsounD session, which
is used for the storage of a unix domain socket. A race condition
exists in the creation of this socket which allows a local attacker to
cause an arbitrary file or directory owned by the user running esound
to become world-writable. This can give the attacker access to the
victim's account, or lead to a system compromise if esound is run by
root.
The esound 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 3700 third-party applications in a ready-to-install
format. The ports collections shipped with FreeBSD 4.0 and 3.5 contain
this problem, but it was corrected prior to the release of FreeBSD
4.1.
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
Local users can cause files or directories owned by the target user to
become world-writable when that user runs the esd daemon (e.g. by
starting a GNOME session), allowing a security breach of that user
account (or the entire system if esd is run by root)
If you have not chosen to install the esound port/package, then your
system is not vulnerable to this problem.
IV. Workaround
Deinstall the esound port/package, if you have installed it (see the
pkg_delete(1) manual page for more information).
V. Solution
One of the following:
1) Upgrade your entire ports collection and rebuild the esound port.
2) Deinstall the old package and install a new package dated after the
correction date, obtained from:
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/audio/esound-0.2.19.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/audio/esound-0.2.19.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/audio/esound-0.2.19.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/audio/esound-0.2.19.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/audio/esound-0.2.19.tgz
3) download a new port skeleton for the esound 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-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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