VNC Security Type Enforcement Failure Remote Authentication Bypass

critical Nessus Plugin ID 21564

Synopsis

The remote VNC server is affected by multiple authentication bypass vulnerabilities.

Description

The version of VNC server running on the remote host is affected by the following vulnerabilities :

- A flaw exists in RealVNC due to an error when handling password authentication. A remote attacker can exploit this to bypass authentication by using a specially crafted request in which the client specifies an insecure security type (e.g., 'Type 1 - None'), which is accepted even if not offered by the server.
(CVE-2006-2369)

- A flaw exists in LibVNCServer within file auth.c due to an error when handling password authentication. A remote attacker can exploit this to bypass authentication by using a specially crafted request in which the client specifies an insecure security type (e.g., 'Type 1 - None'), which is accepted even if not offered by the server. (CVE-2006-2450)

Solution

If using RealVNC, upgrade to RealVNC Free Edition 4.1.2 / Personal Edition 4.2.3 / Enterprise Edition 4.2.3 or later.

If using LibVNCServer, upgrade to version 0.8.2 or later.

See Also

http://www.nessus.org/u?ef2b8a64

http://www.nessus.org/u?8a2c16a0

http://www.nessus.org/u?b218067e

http://www.nessus.org/u?519d872d

https://github.com/LibVNC/libvncserver

Plugin Details

Severity: Critical

ID: 21564

File Name: realvnc_auth_bypass.nasl

Version: 1.30

Type: remote

Family: Misc.

Published: 5/15/2006

Updated: 7/25/2018

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.2

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

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9.1

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

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

Vulnerability Information

CPE: cpe:/a:vnc:realvnc, cpe:/a:libvncserver:libvncserver

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 6/23/2006

Vulnerability Publication Date: 5/15/2006

Exploitable With

CANVAS (CANVAS)

Core Impact

Reference Information

CVE: CVE-2006-2369, CVE-2006-2450

BID: 17978, 18977

CERT: 117929