CVE-2000-1226 in Snort
Summary
by MITRE
Snort 1.6, when running in straight ASCII packet logging mode or IDS mode with straight decoded ASCII packet logging selected, allows remote attackers to cause a denial of service (crash) by sending non-IP protocols that Snort does not know about, as demonstrated by an nmap protocol scan.
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Analysis
by VulDB Data Team • 05/28/2018
The vulnerability identified as CVE-2000-1226 represents a critical denial of service flaw in Snort version 1.6 that manifests when the system operates in either straight ASCII packet logging mode or IDS mode with straight decoded ASCII packet logging enabled. This vulnerability specifically targets the packet parsing and logging mechanisms within the network intrusion detection system, creating a scenario where legitimate network traffic can be exploited to disrupt the operation of the security monitoring tool. The flaw occurs when Snort encounters non-IP protocols that it has not been programmed to recognize, leading to an unhandled exception that causes the application to crash and terminate unexpectedly.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within Snort's packet processing pipeline. When the system receives network packets containing protocol identifiers that fall outside the standard IP protocol suite, the logging subsystem fails to properly handle these unknown protocols. This creates a condition where the application attempts to process and log information about these unrecognized packets without proper safeguards, resulting in a segmentation fault or similar memory access violation that terminates the process. The vulnerability is particularly concerning because it can be triggered remotely through network-based attacks, making it exploitable by adversaries without requiring local system access or authentication.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise the integrity of network monitoring operations and potentially create security blind spots. When Snort crashes due to this vulnerability, the network monitoring capabilities are temporarily suspended, leaving the network exposed to attacks that might otherwise be detected and blocked by the intrusion detection system. This creates a window of opportunity for malicious actors to conduct further reconnaissance or execute more sophisticated attacks without detection. The vulnerability is especially problematic in environments where Snort serves as a primary security monitoring tool, as the crash can occur at any time during network traffic processing, making the system unreliable for continuous security operations.
This vulnerability maps to CWE-20, which describes "Improper Input Validation," and demonstrates how inadequate handling of unexpected inputs can lead to system instability and denial of service conditions. From an ATT&CK perspective, this represents a technique that can be categorized under T1499.004, specifically "Endpoint Denial of Service" where adversaries target network monitoring tools to disrupt security operations. The vulnerability also aligns with T1566.001, "Phishing" and T1071.004, "Application Layer Protocol: DNS" as attackers can leverage various network scanning tools like nmap to trigger the vulnerability through legitimate protocol scanning activities. Organizations should implement immediate mitigations including upgrading to patched versions of Snort, implementing network segmentation to limit exposure, and configuring intrusion detection systems with proper input validation and error handling mechanisms to prevent similar vulnerabilities from affecting other security tools in their infrastructure.