CVE-2024-20481
Description
A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the RAVPN service.
This vulnerability is due to resource exhaustion. An attacker could exploit this vulnerability by sending a large number of VPN authentication requests to an affected device. A successful exploit could allow the attacker to exhaust resources, resulting in a DoS of the RAVPN service on the affected device. Depending on the impact of the attack, a reload of the device may be required to restore the RAVPN service. Services that are not related to VPN are not affected.
Cisco Talos discussed these attacks in the blog post Large-scale brute-force activity targeting VPNs, SSH services with commonly used login credentials.
Summary dbcve.org
A resource exhaustion vulnerability in Cisco ASA and FTD Remote Access VPN services allows unauthenticated remote attackers to flood the device with VPN authentication requests, exhausting resources and causing denial of the RAVPN service. The attack may require device reload to restore VPN functionality.
Mitigation
Apply Cisco-supplied patches for ASA and FTD software when available; implement rate-limiting on VPN authentication endpoints and monitor for anomalous authentication patterns as interim mitigations.