CVE-2024-20426 in ASA
Summary
by MITRE • 10/23/2024
A vulnerability in the Internet Key Exchange version 2 (IKEv2) protocol for VPN termination 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) condition on an affected device.
This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending crafted IKEv2 traffic to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 11/06/2024
The vulnerability identified as CVE-2024-20426 represents a critical denial of service weakness within the Internet Key Exchange version 2 protocol implementation of Cisco's security infrastructure products. This flaw affects both Cisco Adaptive Security Appliance software and Cisco Firepower Threat Defense software, which are widely deployed across enterprise networks for perimeter security and threat detection. The vulnerability stems from inadequate input validation mechanisms within the IKEv2 processing logic, creating an exploitable condition that can be leveraged by remote attackers without requiring authentication credentials. The impact of this vulnerability extends beyond simple service disruption as it can cause complete device reloads, effectively removing the security appliance from network operations and potentially leaving the enterprise exposed to other threats during the recovery period.
The technical exploitation of this vulnerability involves sending specifically crafted IKEv2 packets to the targeted device, which then processes these malformed inputs without proper validation checks. When the affected Cisco ASA or FTD device encounters these malicious packets, the insufficient input validation causes the system to enter an unstable state that ultimately results in automatic device reloading. This behavior aligns with CWE-20, "Improper Input Validation," which is a fundamental weakness that occurs when software does not properly validate inputs from external sources. The vulnerability demonstrates how protocol implementation flaws can be weaponized to create complete service outages, as the device's response to malformed IKEv2 traffic escalates from simple processing errors to full system restarts. The attack vector is particularly concerning as it operates entirely over the network without requiring any form of authentication, making it accessible to any attacker with network connectivity to the vulnerable device.
From an operational perspective, this vulnerability creates significant risk for organizations relying on Cisco ASA and FTD appliances for their network security posture. The DoS condition can result in immediate loss of network connectivity, potentially disrupting business operations and leaving critical network segments unprotected during the device recovery process. Network administrators may experience challenges in detecting and responding to such attacks since they appear as legitimate network traffic patterns, making them difficult to distinguish from normal operational behavior. The vulnerability also has implications for network resilience and business continuity planning, as organizations must now account for the possibility of unauthenticated remote attacks causing complete security appliance failures. This risk is compounded by the fact that these devices typically operate as critical infrastructure components, and their failure can cascade into broader network disruptions. The vulnerability's impact is further exacerbated by the fact that it affects both ASA and FTD platforms, meaning organizations with mixed deployments face increased complexity in their remediation efforts.
Mitigation strategies for CVE-2024-20426 should prioritize immediate patch application from Cisco, as the vendor has released software updates addressing the input validation deficiencies in the IKEv2 implementation. Organizations should implement network segmentation and access controls to limit exposure of vulnerable devices to untrusted networks, while also considering temporary disabling of IKEv2 functionality if not immediately required. Network monitoring should be enhanced to detect unusual IKEv2 traffic patterns that might indicate exploitation attempts, and security teams should establish incident response procedures specifically addressing device reload events. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing robust network security monitoring to identify potential exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving service stoppage and system reloads, which are part of the adversary's toolkit for creating operational disruption and potentially gaining further access to network resources. Organizations should also consider implementing network access control lists to restrict IKEv2 traffic to only trusted sources and establish baseline network behavior to better detect anomalous traffic patterns that could indicate exploitation attempts.