PuTTY CVE-2019-17069 Denial of Service Vulnerability

Description

PuTTY is prone to a denial-of-service vulnerability. An attacker can exploit this issue to cause a denial-of-service condition. Versions prior to PuTTY 0.73 are vulnerable.

Technologies Affected

• Simon Tatham PuTTY 0.45
• Simon Tatham PuTTY 0.46
• Simon Tatham PuTTY 0.47
• Simon Tatham PuTTY 0.49
• Simon Tatham PuTTY 0.50
• Simon Tatham PuTTY 0.51
• Simon Tatham PuTTY 0.53
• Simon Tatham PuTTY 0.54
• Simon Tatham PuTTY 0.55
• Simon Tatham PuTTY 0.56
• Simon Tatham PuTTY 0.57
• Simon Tatham PuTTY 0.58
• Simon Tatham PuTTY 0.59
• Simon Tatham PuTTY 0.6
• Simon Tatham PuTTY 0.60
• Simon Tatham PuTTY 0.61
• Simon Tatham PuTTY 0.62
• Simon Tatham PuTTY 0.63
• Simon Tatham PuTTY 0.64
• Simon Tatham PuTTY 0.65
• Simon Tatham PuTTY 0.66
• Simon Tatham PuTTY 0.68
• Simon Tatham PuTTY 0.71
• Simon Tatham PuTTY 0.72

Recommendations

Block external access at the network boundary, unless external parties require service.
Filter access to the affected computer at the network boundary if global access isn’t needed. Restricting access to only trusted computers and networks might greatly reduce the likelihood of a successful exploit.

Run all software as a nonprivileged user with minimal access rights.
When possible, run client software as regular user accounts with limited access to system resources. This may limit the immediate consequences of client-side vulnerabilities.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to detect and block attacks and anomalous activity such as requests containing suspicious URI sequences. Since the webserver may log such requests, review logs regularly.

Updates are available. Please see the references or vendor advisory for more information.