GLSA 200511-17: FUSE: mtab corruption through fusermount

http://security.gentoo.org/

Severity:	normal
Title:	FUSE: mtab corruption through fusermount
Date:	11/22/2005
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	Architecture(s)
sys-fs/fuse	< 2.4.1-r1	>= 2.4.1-r1	All supported architectures

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

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 security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.