CVE-2024-20260 in ASA
Summary
by MITRE • 10/23/2024
A vulnerability in the VPN and management web servers of the Cisco Adaptive Security Virtual Appliance (ASAv) and Cisco Secure Firewall Threat Defense Virtual (FTDv), formerly Cisco Firepower Threat Defense Virtual, platforms could allow an unauthenticated, remote attacker to cause the virtual devices to run out of system memory, which could cause SSL VPN connection processing to slow down and eventually cease all together.
This vulnerability is due to a lack of proper memory management for new incoming SSL/TLS connections on the virtual platforms. An attacker could exploit this vulnerability by sending a large number of new incoming SSL/TLS connections to the targeted virtual platform. A successful exploit could allow the attacker to deplete system memory, resulting in a denial of service (DoS) condition. The memory could be reclaimed slowly if the attack traffic is stopped, but a manual reload may be required to restore operations quickly.
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Analysis
by VulDB Data Team • 10/25/2024
The vulnerability identified as CVE-2024-20260 affects critical network security infrastructure deployed by Cisco through their Adaptive Security Virtual Appliance (ASAv) and Cisco Secure Firewall Threat Defense Virtual (FTDv) platforms. These virtualized security appliances serve as essential components in enterprise network defense, providing firewall capabilities, intrusion prevention, and secure remote access through SSL VPN services. The affected platforms operate in environments where maintaining continuous network availability and secure access is paramount, making this vulnerability particularly concerning for organizations relying on these virtual security solutions for their network perimeter protection.
This vulnerability stems from inadequate memory management practices within the SSL/TLS connection handling mechanisms of the affected virtual appliances. Specifically, the system fails to properly implement rate limiting or connection throttling for new incoming SSL/TLS connections, allowing an attacker to continuously establish new connections without sufficient resource allocation controls. The flaw manifests when the system allocates memory for each new connection without proper validation or limitation of concurrent connection attempts, leading to unbounded memory consumption. This represents a classic memory exhaustion vulnerability that aligns with CWE-400, which catalogs improper resource management issues in software systems, and specifically relates to CWE-770, which addresses allocation of resources without limits or with insufficient limits.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire security posture of affected networks. An unauthenticated remote attacker can exploit this weakness by flooding the system with numerous simultaneous SSL/TLS connection requests, causing progressive memory depletion that ultimately leads to complete service denial. The system exhibits gradual performance degradation before complete cessation of SSL VPN functionality, creating a window where network administrators may not immediately recognize the extent of the attack. This vulnerability directly maps to the ATT&CK technique T1499.004, which describes resource exhaustion attacks targeting network services, and represents a sophisticated form of denial of service that can be executed from outside the network perimeter without requiring any authentication credentials or privileged access.
Organizations must implement immediate mitigations to protect their deployed virtual appliances from exploitation of this vulnerability. The most effective immediate response involves configuring connection rate limiting and implementing proper SSL/TLS connection handling policies that prevent unlimited resource allocation for new connections. Network administrators should also establish monitoring thresholds to detect unusual connection patterns and memory usage spikes that may indicate an ongoing attack. Cisco has released software updates addressing this vulnerability, and organizations should prioritize applying these patches through established change management processes. Additionally, implementing network-level controls such as firewall rules that limit connection rates from specific source IP ranges can provide additional defense-in-depth measures. The manual reload requirement mentioned in the vulnerability description indicates that even after stopping attack traffic, administrators may need to perform system restarts to fully restore normal operations, emphasizing the critical nature of rapid response and recovery procedures.