Check Point Advisories

LibVNCServer LibVNCClient FramebufferUpdate Rectangle Heap Buffer Overflow (CVE-2016-9941)

Vulnerability
Protection

Check Point Reference:	CPAI-2017-0060
Date Published:	22 Jan 2017
Severity:	High
Last Updated:	Tuesday 08 August, 2023
Source:	LibVNC Development Team
Industry Reference:	CVE-2016-9941
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?	LibVNCServer Development Team LibVNCServer prior to 0.9.11
Vulnerability Description	A heap-based buffer overflow has been reported in LibVNCServer LibVNCClient. The vulnerability is due to improper handling of FramebufferUpdate messages with specially crafted rectangles. A remote attacker could exploit this vulnerability by enticing a user to connect to a malicious VNC server and sending a crafted FramebufferUpdate message to a vulnerable target client.

Protection Overview

This protection will detect and block attempts to exploit this vulnerability.

In order for the protection to be activated, update your Security Gateway product to the latest IPS update. For information on how to update IPS, go to SBP-2006-05, click on Protection tab and select the version of your choice.

Security Gateway R81 / R80 / R77 / R75

In the IPS tab, click Protections and find the LibVNCServer LibVNCClient FramebufferUpdate Rectangle Heap Buffer Overflow protection using the Search tool and Edit the protection's settings.
Install policy on all Security Gateways.

This protection's log will contain the following information:

Attack Name: Web Client Enforcement Violation.
Attack Information: LibVNCServer LibVNCClient FramebufferUpdate Rectangle Heap Buffer Overflow