CVE-2022-20751 in Firepower Threat Defense
Summary
by MITRE • 05/03/2022
A vulnerability in the Snort detection engine integration for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause unlimited memory consumption, which could lead to a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient memory management for certain Snort events. An attacker could exploit this vulnerability by sending a series of crafted IP packets that would generate specific Snort events on an affected device. A sustained attack could cause an out of memory condition on the affected device. A successful exploit could allow the attacker to interrupt all traffic flowing through the affected device. In some circumstances, the attacker may be able to cause the device to reload, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 05/05/2022
The vulnerability identified as CVE-2022-20751 represents a critical memory management flaw within the Snort detection engine integration of Cisco Firepower Threat Defense software, specifically targeting the device's ability to handle certain network events. This weakness resides in the software's handling of specific Snort events that occur during packet processing, creating a condition where memory allocation becomes unbounded under certain attack scenarios. The vulnerability stems from inadequate memory management protocols that fail to properly monitor and limit memory consumption when processing crafted network traffic patterns, making it particularly dangerous for network security appliances that must maintain continuous operation.
The technical exploitation of this vulnerability involves an unauthenticated remote attacker sending a series of specifically crafted IP packets designed to trigger particular Snort events within the FTD software stack. These crafted packets are engineered to generate memory-intensive processing conditions that bypass normal memory management controls. The flaw operates at the intersection of network packet processing and event handling within the Snort engine, where each malicious packet triggers memory allocation that accumulates without proper bounds checking or memory cleanup mechanisms. This type of vulnerability aligns with CWE-129, which addresses insufficient input validation, and more specifically with CWE-772, concerning missing release of memory after effective lifetime, as the system fails to properly manage memory resources during event processing.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromising the entire network infrastructure that relies on the affected FTD device for security operations. When exploited successfully, the vulnerability can cause unlimited memory consumption that ultimately leads to a complete denial of service condition, effectively halting all network traffic passing through the device. The sustained nature of the attack means that even brief periods of exploitation can cause permanent memory exhaustion, forcing the device into a state where it cannot process legitimate network traffic. In some cases, the memory exhaustion may trigger automatic device reloads, creating additional service interruption and potentially providing attackers with opportunities for further exploitation or disruption. The attack vector operates entirely over the network without requiring authentication, making it particularly dangerous for devices exposed to untrusted network segments.
Organizations affected by this vulnerability should implement immediate mitigations including network segmentation to limit exposure, deploying rate limiting controls to reduce the impact of crafted packet streams, and applying the latest security patches provided by Cisco. The vulnerability's classification under the ATT&CK framework would place it within the Defense Evasion and Resource Exhaustion tactics, specifically addressing techniques that involve consuming system resources to prevent legitimate operations. Network administrators should also consider implementing intrusion detection systems that can identify and block the specific packet patterns associated with this attack, as well as monitoring for unusual memory consumption patterns that may indicate exploitation attempts. The combination of proper patch management, network access controls, and continuous monitoring provides the most effective defense against this particular memory exhaustion vulnerability that could compromise network security infrastructure.