CVE Vulnerabilities

CVE-2016-6253

Improper Link Resolution Before File Access ('Link Following')

Published: Jan 20, 2017 | Modified: Jan 20, 2017
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
7.2 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C
RedHat/V2
RedHat/V3
Ubuntu

mail.local in NetBSD versions 6.0 through 6.0.6, 6.1 through 6.1.5, and 7.0 allows local users to change ownership of or append data to arbitrary files on the target system via a symlink attack on the user mailbox.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Name Vendor Start Version End Version
Netbsd Netbsd 6.1.1 6.1.1
Netbsd Netbsd 6.1.3 6.1.3
Netbsd Netbsd 6.0 6.0
Netbsd Netbsd 6.1.4 6.1.4
Netbsd Netbsd 6.0.4 6.0.4
Netbsd Netbsd 6.0.6 6.0.6
Netbsd Netbsd 7.0 7.0
Netbsd Netbsd 6.0.2 6.0.2
Netbsd Netbsd 6.0.5 6.0.5
Netbsd Netbsd 6.1.2 6.1.2
Netbsd Netbsd 6.0.1 6.0.1
Netbsd Netbsd 6.1.5 6.1.5
Netbsd Netbsd 6.0.3 6.0.3
Netbsd Netbsd 6.1 6.1

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References