Rechercher
Contactez-nous Suivez-nous sur Twitter En francais English Language
 

Freely subscribe to our NEWSLETTER

Newsletter FR

Newsletter EN

Vulnérabilités

Unsubscribe

Vigil@nce: Linux kernel, privilege elevation via fsuid

April 2009 by Vigil@nce

A NFS client can elevate his privileges on a NFS server, via a
vulnerability related to fsuid.

 Severity: 2/4
 Consequences: administrator access/rights
 Provenance: user account
 Means of attack: no proof of concept, no attack
 Ability of attacker: expert (4/4)
 Confidence: confirmed by the editor (5/5)
 Diffusion of the vulnerable configuration: high (3/3)
 Creation date: 23/04/2009

IMPACTED PRODUCTS

 Linux kernel

DESCRIPTION OF THE VULNERABILITY

The "fsuid" value indicates the identifier of the user who handles
files. For example, a NFS server runs as root and uses fsuid to
create and modify files with privileges of the connected user.

The CAP_MKNOD (device creation) and CAP_LINUX_IMMUTABLE (special
attributes) capabilities have to be suppressed when fsuid is
different from 0. However, this is not the case: if the user has
these capabilities, they are not suppressed.

An attacker who is root on a NFS client can therefore grant the
CAP_MKNOD capability to a user. He can then connect with this
account to the NFS server. He can create a device on the
filesystem. The NFS server does not refuse this operation. The
device can for example be used to access to the hard drive of the
NFS server.

CHARACTERISTICS

 Identifiers: BID-34695, VIGILANCE-VUL-8664
 Url: http://vigilance.fr/vulnerability/Linux-kernel-privilege-elevation-via-fsuid-8664

To change your email preferences (frequency, severity threshold, format):
https://vigilance.fr/?action=2041549901&langue=2


See previous articles

    

See next articles


Your podcast Here

New, you can have your Podcast here. Contact us for more information ask:
Marc Brami
Phone: +33 1 40 92 05 55
Mail: ipsimp@free.fr

All new podcasts