VNC Security Type Enforcement Failure Remote Authentication Bypass

critical Nessus Plugin ID 21564
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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

Dependencies: vnc.nasl

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

Temporal Vector: CVSS2#E:F/RL:OF/RC:C

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:2.3:a:libvncserver:libvncserver:*:*:*:*:*:*:*:*, cpe:2.3:a:vnc:realvnc:*:*:*:*:*:*:*:*

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

EDB-ID: 1791