GLSA 201612-02: DavFS2: Local privilege escalation

http://security.gentoo.org/

Severity:	normal
Title:	DavFS2: Local privilege escalation
Date:	12/02/2016
Bugs:	#485232
ID:	201612-02

Synopsis

A vulnerability in DavFS2 allows local users to gain root privileges.

Background

DavFS2 is a file system driver that allows you to mount a WebDAV server as a local disk drive.

Affected packages

Package	Vulnerable	Unaffected	Architecture(s)
net-fs/davfs2	< 1.5.2	>= 1.5.2	All supported architectures

Description

DavFS2 installs “/usr/sbin/mount.davfs” as setuid root. This utility uses “system()” to call “/sbin/modprobe”.

While the call to “modprobe” itself cannot be manipulated, a local authenticated user can set the “MODPROBE_OPTIONS” environment variable to pass a user controlled path, allowing the loading of an arbitrary kernel module.

Impact

A local user could gain root privileges.

Workaround

The system administrator should ensure that all modules the “mount.davfs” utility tries to load are loaded upon system boot before any local user can call the utility.

An additional defense measure can be implemented by enabling the Linux kernel module signing feature. This assists in the prevention of arbitrary modules being loaded.

Resolution

All DavFS2 users should upgrade to the latest version:

      # emerge --sync
      # emerge --ask --oneshot --verbose ">=net-fs/davfs2-1.5.2"

References

CVE-2013-4362

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-201612-02.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.