CVE-2024-20508 in UTD SNORT IPS Engine Software
Summary
by MITRE • 09/25/2024
A vulnerability in Cisco Unified Threat Defense (UTD) Snort Intrusion Prevention System (IPS) Engine for Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass configured security policies or cause a denial of service (DoS) condition on an affected device.
This vulnerability is due to insufficient validation of HTTP requests when they are processed by Cisco UTD Snort IPS Engine. An attacker could exploit this vulnerability by sending a crafted HTTP request through an affected device. A successful exploit could allow the attacker to trigger a reload of the Snort process. If the action in case of Cisco UTD Snort IPS Engine failure is set to the default, fail-open, successful exploitation of this vulnerability could allow the attacker to bypass configured security policies. If the action in case of Cisco UTD Snort IPS Engine failure is set to fail-close, successful exploitation of this vulnerability could cause traffic that is configured to be inspected by Cisco UTD Snort IPS Engine to be dropped.
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Analysis
by VulDB Data Team • 10/04/2024
The vulnerability identified as CVE-2024-20508 represents a critical weakness in Cisco Unified Threat Defense systems that specifically impacts the Snort Intrusion Prevention System engine running on Cisco IOS XE Software. This flaw exists within the HTTP request processing mechanism where inadequate input validation creates opportunities for malicious actors to manipulate the system's security posture. The vulnerability is particularly concerning because it operates at the network level where security policies are enforced, making it a significant threat to enterprise network integrity and protection.
The technical implementation of this vulnerability stems from insufficient validation mechanisms within the Snort IPS engine's HTTP processing module. When an attacker crafts and sends specifically designed HTTP requests through an affected Cisco UTD device, the system fails to properly validate these requests before processing them. This validation gap allows malicious payloads to bypass normal security checks and potentially trigger unintended system behavior. The flaw operates at the application layer where HTTP traffic is inspected, making it a direct threat to network security policy enforcement.
The operational impact of this vulnerability manifests in two distinct but equally dangerous scenarios depending on the system's configured failure handling behavior. When the Cisco UTD Snort IPS Engine is set to default fail-open mode, successful exploitation enables attackers to bypass configured security policies entirely, effectively allowing malicious traffic to pass through network defenses without detection or blocking. This creates a significant security risk where unauthorized access and data exfiltration become possible. Alternatively, when configured in fail-close mode, exploitation causes denial of service conditions where legitimate traffic that should be inspected by the IPS engine gets dropped, creating network disruption and potential business continuity issues.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-20, which describes "Improper Input Validation" as a fundamental weakness that enables various attack vectors including those that bypass security controls. The ATT&CK framework categorizes this vulnerability under T1190, "Exploit Public-Facing Application," and potentially T1499, "Endpoint Denial of Service," depending on the exploitation outcome. The attack surface is particularly relevant for enterprise networks that rely heavily on Cisco UTD for network security, as these systems often serve as primary defense mechanisms against external threats and internal security violations.
The exploitation of this vulnerability demonstrates the importance of proper input validation in security-critical systems and highlights the need for robust error handling mechanisms. Organizations should prioritize immediate remediation through official Cisco patches while also implementing network segmentation and monitoring to detect potential exploitation attempts. The vulnerability underscores the necessity of maintaining up-to-date security configurations and conducting regular vulnerability assessments to identify and address similar weaknesses in network infrastructure components that serve as primary security enforcement points.