A vulnerability in the Secure Sockets Layer (SSL)/Transport Layer Security (TLS) handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust memory resources on the affected device, leading to a denial of service (DoS) condition. The vulnerability is due to improper resource management for inbound SSL/TLS connections. An attacker could exploit this vulnerability by establishing multiple SSL/TLS connections with specific conditions to the affected device. A successful exploit could allow the attacker to exhaust the memory on the affected device, causing the device to stop accepting new SSL/TLS connections and resulting in a DoS condition for services on the device that process SSL/TLS traffic. Manual intervention is required to recover an affected device.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Firepower_threat_defense | Cisco | 6.2.3 (including) | 6.2.3.16 (excluding) |
| Firepower_threat_defense | Cisco | 6.3.0 (including) | 6.3.0.6 (excluding) |
| Firepower_threat_defense | Cisco | 6.4.0 (including) | 6.4.0.9 (excluding) |
| Firepower_threat_defense | Cisco | 6.5.0 (including) | 6.5.0.5 (excluding) |
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.