Cisco Adaptive Security Appliance (ASA) Software Secure Sockets Layer (SSL) VPN Improper Handling of Exceptional Conditions Encoding Error Vulnerability

Summary

A vulnerability in the Secure Sockets Layer (SSL) VPN feature of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition that prevents the creation of new SSL/Transport Layer Security (TLS) connections to an affected device.

Credit:

The information has been provided by Vendor.

The original article can be found at: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20191002-asa-ssl-vpn-dos

 


Details

The vulnerability is due to incorrect handling of Base64-encoded strings. An attacker could exploit this vulnerability by opening many SSL VPN sessions to an affected device. The attacker would need to have valid user credentials on the affected device to exploit this vulnerability. A successful exploit could allow the attacker to overwrite a special system memory location, which will eventually result in memory allocation errors for new SSL/TLS sessions to the device, preventing successful establishment of these sessions. A reload of the device is required to recover from this condition. Established SSL/TLS connections to the device and SSL/TLS connections through the device are not affected.

Vulnerable Systems:

Cisco ASA Software.

CVE Information:

CVE-2019-12677

Disclosure Timeline:

Published Date:10/02/2019