CVE-2016-6368 in FirePOWER
Summary
by MITRE
A vulnerability in the detection engine parsing of Pragmatic General Multicast (PGM) protocol packets for Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the Snort process unexpectedly restarting. The vulnerability is due to improper input validation of the fields in the PGM protocol packet. An attacker could exploit this vulnerability by sending a crafted PGM packet to the detection engine on the targeted device. An exploit could allow the attacker to cause a DoS condition if the Snort process restarts and traffic inspection is bypassed or traffic is dropped. This vulnerability affects Cisco Firepower System Software that has one or more file action policies configured and is running on any of the following Cisco products: Adaptive Security Appliance (ASA) 5500-X Series with FirePOWER Services; Adaptive Security Appliance (ASA) 5500-X Series Next-Generation Firewalls; Advanced Malware Protection (AMP) for Networks, 7000 Series Appliances; Advanced Malware Protection (AMP) for Networks, 8000 Series Appliances; Firepower 4100 Series Security Appliances; FirePOWER 7000 Series Appliances; FirePOWER 8000 Series Appliances; Firepower 9300 Series Security Appliances; FirePOWER Threat Defense for Integrated Services Routers (ISRs); Industrial Security Appliance 3000; Sourcefire 3D System Appliances; Virtual Next-Generation Intrusion Prevention System (NGIPSv) for VMware. Fixed versions: 5.4.0.10 5.4.1.9 6.0.1.3 6.1.0 6.2.0. Cisco Bug IDs: CSCuz00876.
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Analysis
by VulDB Data Team • 11/26/2024
The vulnerability described in CVE-2016-6368 represents a critical denial of service weakness within Cisco Firepower System Software that specifically targets the Pragmatic General Multicast (PGM) protocol packet parsing functionality. This flaw exists within the detection engine's handling of PGM protocol packets, where insufficient input validation allows maliciously crafted packets to trigger unexpected behavior in the Snort process. The issue manifests as an unauthorized remote attacker being able to cause the Snort process to restart unexpectedly, thereby creating a denial of service condition that compromises network traffic inspection capabilities. The vulnerability stems from improper validation of fields within PGM protocol packets, making it possible for attackers to exploit this weakness through carefully constructed packet payloads that manipulate the system's parsing logic.
The technical exploitation of this vulnerability involves sending specially crafted PGM packets to the targeted Cisco Firepower device, which then processes these packets through the detection engine. When the system encounters malformed or unexpected PGM packet fields, the validation mechanisms fail to properly handle the input, leading to a cascading failure that results in the Snort process crashing and restarting. This restart operation effectively bypasses traffic inspection mechanisms and causes traffic to be dropped or improperly handled, creating a complete denial of service scenario for the affected network security appliance. The flaw demonstrates a classic input validation weakness that can be categorized under CWE-20, which addresses improper input validation in software systems. The vulnerability affects multiple Cisco products including various ASA 5500-X Series appliances, Firepower series security appliances, and Advanced Malware Protection systems, indicating a widespread impact across the Cisco security portfolio.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromising network security posture and availability. When the Snort process restarts due to the malformed PGM packet processing, the device loses its ability to inspect and analyze network traffic for security threats, creating a window of vulnerability where malicious traffic can pass through undetected. This represents a significant concern for organizations relying on Cisco Firepower systems for network security monitoring and intrusion prevention, as the DoS condition can persist until manual intervention occurs or the system automatically recovers. The vulnerability's remote and unauthenticated nature makes it particularly dangerous as attackers can exploit it without requiring any credentials or physical access to the target device. This aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how protocol parsing vulnerabilities can be leveraged to achieve system-level disruption. Organizations using affected Cisco products face the risk of extended downtime and potential security gaps during the DoS event, as the traffic inspection capabilities are temporarily disabled while the Snort process restarts and reinitializes.
Mitigation strategies for this vulnerability require immediate implementation of software updates to patched versions including 5.4.0.10, 5.4.1.9, 6.0.1.3, 6.1.0, and 6.2.0 as specified by Cisco. Network administrators should also consider implementing network segmentation and access controls to limit exposure of affected devices to untrusted networks, while monitoring for unusual traffic patterns that might indicate exploitation attempts. Additional defensive measures include configuring rate limiting on PGM protocol traffic where possible and implementing robust network monitoring solutions to detect service restart events and potential exploitation attempts. Organizations should also review their incident response procedures to ensure rapid detection and recovery from such DoS conditions, as the automatic restart of the Snort process may not be immediately apparent to network operators. The vulnerability serves as a reminder of the critical importance of proper input validation in network security systems and demonstrates how protocol-specific parsing flaws can lead to system-wide availability issues. Regular security assessments and vulnerability management programs should include thorough testing of protocol handling capabilities to identify similar weaknesses before they can be exploited by malicious actors in the field.