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FreeBSD : openssh -- command injection when X11Forwarding is enabled (e4644df8-e7da-11e5-829d-c80aa9043978)

medium Nessus Plugin ID 89897

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Synopsis

The remote FreeBSD host is missing a security-related update.

Description

The OpenSSH project reports :

Missing sanitisation of untrusted input allows an authenticated user who is able to request X11 forwarding to inject commands to xauth(1).

Injection of xauth commands grants the ability to read arbitrary files under the authenticated user's privilege, Other xauth commands allow limited information leakage, file overwrite, port probing and generally expose xauth(1), which was not written with a hostile user in mind, as an attack surface.

Mitigation :

Set X11Forwarding=no in sshd_config. This is the default.

For authorized_keys that specify a 'command' restriction, also set the 'restrict' (available in OpenSSH >=7.2) or 'no-x11-forwarding' restrictions.

Solution

Update the affected package.

See Also

http://www.openssh.com/txt/x11fwd.adv

http://www.nessus.org/u?8a7b4781

Plugin Details

Severity: Medium

ID: 89897

File Name: freebsd_pkg_e4644df8e7da11e5829dc80aa9043978.nasl

Version: 2.8

Type: local

Published: 3/14/2016

Updated: 1/4/2021

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.8

CVSS v2

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.3

Vector: CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:N

CVSS v3

Risk Factor: Medium

Base Score: 6.4

Temporal Score: 5.8

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:openssh-portable, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 3/11/2016

Vulnerability Publication Date: 3/11/2016

Reference Information

CVE: CVE-2016-3115

FreeBSD: SA-16:14.openssh