A vulnerability in the Decryption Policy Default Action functionality of the Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to bypass a configured drop policy and allow traffic onto the network that should have been denied. The vulnerability is due to the incorrect handling of SSL-encrypted traffic when Decrypt for End-User Notification is disabled in the configuration. An attacker could exploit this vulnerability by sending a SSL connection through the affected device. A successful exploit could allow the attacker to bypass a configured drop policy to block specific SSL connections. Releases 10.1.x and 10.5.x are affected.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Web_security_appliance | Cisco | 10.1.0-204 (including) | 10.1.0-204 (including) |
| Web_security_appliance | Cisco | 10.5.2-072 (including) | 10.5.2-072 (including) |
| Web_security_appliance | Cisco | 11.5.1-fcs-115 (including) | 11.5.1-fcs-115 (including) |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.