CVE-2020-3196 in ASA
Summary
by MITRE
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.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/15/2020
The vulnerability identified as CVE-2020-3196 represents a critical resource exhaustion flaw within the SSL/TLS processing mechanisms of Cisco's security infrastructure products. This weakness specifically affects Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software, which are widely deployed across enterprise networks for perimeter security and threat detection. The vulnerability stems from inadequate memory management practices within the SSL/TLS handler component, creating an exploitable condition that can be leveraged by remote attackers without requiring authentication credentials. The flaw manifests when the system fails to properly terminate or manage SSL/TLS connection states, leading to progressive memory consumption that eventually exhausts available resources. This issue is particularly concerning given the foundational role these devices play in network security operations, where their availability directly impacts the organization's ability to maintain secure communications and detect malicious activities.
The technical exploitation of CVE-2020-3196 involves an attacker establishing multiple SSL/TLS connections to the vulnerable device while maintaining specific connection parameters that trigger the memory management failure. The vulnerability operates through improper handling of SSL/TLS handshake processes and connection state tracking, where each connection consumes memory resources that are not adequately released upon connection termination. This resource leak occurs in the SSL/TLS processing pipeline where the device maintains connection contexts and associated data structures even after the connection should be considered closed. The flaw aligns with CWE-400, which categorizes resource exhaustion vulnerabilities, and specifically demonstrates characteristics of improper resource management in network security appliances. Attackers can systematically establish connections with varying parameters to maximize memory consumption, creating a gradual but steady degradation of the device's operational capacity until complete service disruption occurs.
The operational impact of this vulnerability extends beyond simple service disruption to encompass significant business continuity implications for organizations relying on affected Cisco security appliances. When memory exhaustion occurs, the affected device becomes incapable of processing new SSL/TLS connections, effectively blocking secure communication channels that are critical for network operations. This DoS condition affects not only the device's ability to perform its primary security functions but also impacts the entire network infrastructure that depends on secure communications for authentication, data protection, and service availability. The vulnerability's remote nature means that attackers can exploit it from anywhere on the internet without requiring physical access or network proximity, making it particularly dangerous for organizations with exposed security appliances. Recovery from such an attack requires manual intervention, including device reboot operations, which can result in temporary service outages and potential data loss during the recovery process. The incident also creates opportunities for attackers to conduct further reconnaissance or maintain persistent access through the disruption of security monitoring capabilities.
Organizations should implement immediate mitigations including applying the latest security patches provided by Cisco, which address the underlying memory management issues in the SSL/TLS handler. Network administrators should also consider implementing connection rate limiting and monitoring mechanisms to detect unusual patterns of SSL/TLS connection establishment that could indicate exploitation attempts. The implementation of intrusion detection systems capable of identifying the specific connection patterns associated with this vulnerability can provide early warning capabilities. Additionally, organizations should review their network architecture to ensure that critical security appliances are not directly exposed to untrusted networks and consider implementing additional layers of security controls. From an ATT&CK framework perspective, this vulnerability maps to techniques involving resource exhaustion and denial of service, representing a significant threat to network availability and security operations. The vulnerability also highlights the importance of proper software lifecycle management and regular security assessments to identify and remediate similar weaknesses before they can be exploited by malicious actors.