CVE-2003-0209 in Snort
Summary
by MITRE
Integer overflow in the TCP stream reassembly module (stream4) for Snort 2.0 and earlier allows remote attackers to execute arbitrary code via large sequence numbers in packets, which enable a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability described in CVE-2003-0209 represents a critical security flaw within the Snort intrusion detection system version 2.0 and earlier, specifically within its TCP stream reassembly module known as stream4. This integer overflow vulnerability occurs when the system processes TCP packets containing large sequence numbers, creating a condition where the software fails to properly handle the mathematical operations involved in reassembling TCP streams. The flaw stems from inadequate input validation and boundary checking within the stream4 module, which is responsible for reconstructing TCP connections from individual packets.
The technical implementation of this vulnerability exploits the fundamental way TCP sequence numbers are processed during network traffic analysis. When Snort encounters TCP packets with sequence numbers that exceed the maximum value that can be represented by the integer data type used in the stream4 module, an integer overflow occurs. This overflow results in a negative or unexpectedly large integer value that subsequently triggers a heap-based buffer overflow during the reassembly process. The heap corruption occurs because the system attempts to allocate memory based on the corrupted integer values, leading to memory layout inconsistencies that malicious actors can exploit to execute arbitrary code with the privileges of the Snort process.
The operational impact of this vulnerability is severe and far-reaching within network security environments that rely on Snort for intrusion detection. Remote attackers can leverage this flaw to gain unauthorized code execution capabilities on systems running vulnerable versions of Snort, potentially leading to complete system compromise. The vulnerability affects network monitoring and security infrastructure that depends on Snort's TCP stream reassembly functionality, creating a significant risk for organizations that use this tool for network traffic analysis and intrusion detection. The exploitability of this vulnerability means that attackers do not require local access or authentication to leverage the flaw, making it particularly dangerous in networked environments where Snort is deployed to monitor traffic.
The vulnerability aligns with CWE-190, which describes integer overflow conditions that can lead to buffer overflows, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter. Organizations using vulnerable versions of Snort should immediately upgrade to patched versions of the software to address this critical flaw. Mitigation strategies include implementing network segmentation to limit exposure, deploying additional network monitoring tools, and ensuring that all Snort installations are updated to versions that include proper integer overflow protections. The fix typically involves implementing proper input validation, using safer integer arithmetic operations, and ensuring that memory allocation calculations are performed with appropriate bounds checking to prevent the overflow conditions that lead to heap corruption and arbitrary code execution.
This vulnerability serves as a classic example of how seemingly minor implementation flaws in security tools can create significant risks for network infrastructure. The integer overflow in the stream4 module demonstrates the importance of robust input validation and memory management practices in security software, particularly in systems that process large volumes of network traffic. The vulnerability's impact extends beyond individual systems to potentially affect entire network security infrastructures that depend on Snort's TCP stream reassembly capabilities, highlighting the critical nature of maintaining up-to-date security tools and the potential consequences of running vulnerable software in production environments.