Gentoo Linux Security Advisory GLSA 200511-17

                                        http://security.gentoo.org/

Severity: Normal
Title: FUSE: mtab corruption through fusermount
Date: November 22, 2005
Bugs: #112902
ID: 200511-17

Synopsis

The fusermount utility from FUSE can be abused to corrupt the /etc/mtab
file contents, potentially allowing a local attacker to set
unauthorized mount options.

Background

FUSE (Filesystem in Userspace) allows implementation of a fully
functional filesystem in a userspace program. The fusermount utility is
used to mount/unmount FUSE file systems.

Affected packages

-------------------------------------------------------------------
 Package      /  Vulnerable  /                          Unaffected
-------------------------------------------------------------------

1 sys-fs/fuse < 2.4.1-r1 >= 2.4.1-r1

Description

Thomas Biege discovered that fusermount fails to securely handle
special characters specified in mount points.

Impact

A local attacker could corrupt the contents of the /etc/mtab file by
mounting over a maliciously-named directory using fusermount,
potentially allowing the attacker to set unauthorized mount options.
This is possible only if fusermount is installed setuid root, which is
the default in Gentoo.

Workaround

There is no known workaround at this time.

Resolution

All FUSE users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-fs/fuse-2.4.1-r1"

References

[ 1 ] CVE-2005-3531
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-3531

Availability

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

http://security.gentoo.org/glsa/glsa-200511-17.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
[email protected] or alternatively, you may file a bug at
http://bugs.gentoo.org.

License

Copyright 2005 Gentoo Foundation, 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/2.0