Freely subscribe to our NEWSLETTER

SYNTHESIS OF THE VULNERABILITY

When the mount.cifs tool is installed suid root, a local attacker
can use a symbolic link, in order to elevate his privileges or to
obtain information.

Severity: 2/4

Consequences: administrator access/rights, privileged
access/rights, user access/rights, data reading

Provenance: user shell

Means of attack: 1 attack

Ability of attacker: technician (2/4)

Confidence: confirmed by the editor (5/5)

Diffusion of the vulnerable configuration: high (3/3)

Creation date: 29/01/2010

IMPACTED PRODUCTS

– Samba

DESCRIPTION OF THE VULNERABILITY

The mount.cifs utility of the Samba suite is used to mount a
remote CIFS/SMB share in a local directory. This tool is
frequently installed suid root.

However, this tool does not atomically check the mount directory.
A local attacker can therefore:

– call mount.cifs to mount a remote share on /home/user/mydir
– during its execution, replace /home/user/mydir by a symbolic
link to /privatedirectory
– wait for mount.cifs to mount the share on /privatedirectory

So, by modifying/reading the content of the share on the remote
server, the local attacker can modify/read to content of
/privatedirectory.

When the mount.cifs tool is installed suid root, a local attacker
can therefore use a symbolic link, in order to elevate his
privileges or to obtain information.

CHARACTERISTICS

Identifiers: 532940, 6853, BID-37992, CVE-2009-3297,
VIGILANCE-VUL-9390

http://vigilance.fr/vulnerability/Samba-privilege-elevation-via-mount-cifs-9390