CVE-2022-20757 in Firepower Threat Defense
Summary
by MITRE • 05/03/2022
A vulnerability in the connection handling function in 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 improper traffic handling when platform limits are reached. An attacker could exploit this vulnerability by sending a high rate of UDP traffic through an affected device. A successful exploit could allow the attacker to cause all new, incoming connections to be dropped, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 05/05/2022
The vulnerability identified as CVE-2022-20757 resides within the connection handling mechanisms of Cisco Firepower Threat Defense (FTD) software, representing a critical weakness that can be exploited remotely without authentication. This flaw specifically manifests when platform resource limits are approached or exceeded, creating a scenario where the system fails to properly manage incoming network traffic. The vulnerability is categorized under CWE-400, which addresses "Uncontrolled Resource Consumption" and falls within the broader category of denial of service conditions that compromise system availability. The attack vector involves sending a high volume of UDP traffic through the affected device, leveraging the software's inadequate handling of traffic limits to disrupt normal operations.
The technical implementation of this vulnerability stems from the software's insufficient state management during peak traffic conditions, where the connection handling function fails to gracefully degrade or reject excessive traffic patterns. When the platform reaches its established limits for concurrent connections or traffic throughput, the system does not properly queue or drop connections in a controlled manner. Instead, the improper traffic handling causes the device to enter a degraded state where it begins dropping all new incoming connections rather than maintaining service for existing connections or implementing proper traffic shaping. This behavior creates a cascading failure where legitimate network traffic is disrupted while malicious traffic continues to consume resources, effectively rendering the device unable to process new connections.
The operational impact of CVE-2022-20757 extends beyond simple service disruption to potentially compromise network security posture and business continuity. Organizations relying on FTD appliances for network defense may find their security infrastructure rendered ineffective during an attack, creating a window where other network threats can bypass protection mechanisms. The vulnerability aligns with ATT&CK technique T1498, which describes "Network Denial of Service" and represents a specific method for achieving system unavailability through resource exhaustion. Network administrators face the challenge of identifying and mitigating this vulnerability while maintaining operational security, as the attack can occur without any authentication requirements, making it particularly dangerous in environments where network access controls may be insufficient.
Mitigation strategies for CVE-2022-20757 should focus on both immediate defensive measures and long-term architectural improvements. Cisco has released software updates addressing this vulnerability through patch management procedures, which should be implemented immediately across all affected devices. Network administrators should also implement rate limiting policies at network boundaries to reduce the volume of UDP traffic reaching FTD appliances, particularly for non-essential services. Additionally, monitoring systems should be configured to detect unusual traffic patterns that might indicate exploitation attempts, with alerting thresholds set below the platform's resource limits to prevent system exhaustion. The implementation of these controls aligns with security frameworks such as NIST SP 800-53 and ISO 27001, which emphasize the importance of resource management and access control in maintaining system availability and security. Organizations should also consider implementing network segmentation strategies to limit the impact scope of such vulnerabilities and establish incident response procedures specifically addressing denial of service conditions in network security appliances.