CVE-2003-0850 in Libnids
Summary
by MITRE
The TCP reassembly functionality in libnids before 1.18 allows remote attackers to cause "memory corruption" and possibly execute arbitrary code via "overlarge TCP packets."
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability identified as CVE-2003-0850 resides within the libnids library version 1.18 and earlier, which serves as a network packet processing and analysis tool widely utilized in intrusion detection systems and network monitoring applications. This flaw specifically targets the TCP reassembly component of the library, which is responsible for reconstructing fragmented TCP packets into complete data streams for analysis. The issue manifests when the library encounters TCP packets that exceed normal size parameters, creating a scenario where memory allocation and handling becomes compromised. This vulnerability falls under the category of memory corruption issues, which are particularly dangerous as they can lead to unpredictable behavior and potential code execution. The affected library is commonly integrated into security tools such as snort, making this vulnerability particularly impactful across network security infrastructure.
The technical mechanism behind this vulnerability involves improper handling of TCP packet fragmentation and reassembly processes. When libnids encounters TCP segments that are excessively large, the library fails to properly validate the packet size limits during the reassembly phase. This leads to memory corruption through buffer overflows or heap corruption, as the system attempts to allocate memory spaces that exceed expected boundaries. The flaw is categorized as a buffer overflow vulnerability and maps to CWE-121, which describes stack-based buffer overflow conditions. The improper input validation during TCP packet processing creates opportunities for attackers to craft malicious packets that trigger the memory corruption, potentially allowing remote code execution. The vulnerability demonstrates characteristics consistent with CWE-787, heap-based buffer overflow, when the oversized packets cause memory corruption in heap-allocated structures used for packet reassembly.
The operational impact of this vulnerability extends significantly across network security environments where libnids is deployed. Attackers can exploit this weakness remotely by sending specially crafted TCP packets that exceed normal size limits, potentially causing the target system to crash or execute arbitrary code. This creates a serious threat to network monitoring and intrusion detection systems that rely on libnids for packet analysis, as these systems become vulnerable to remote compromise. The vulnerability affects systems where libnids is integrated into security appliances, network analyzers, and monitoring tools, potentially allowing attackers to gain unauthorized access to network traffic analysis systems. The impact is particularly severe in environments where these tools are used for security monitoring, as the compromise of such systems could lead to complete network visibility loss and potential data exfiltration.
Mitigation strategies for CVE-2003-0850 primarily focus on upgrading to libnids version 1.18 or later, which contains the necessary patches to address the TCP reassembly memory corruption issues. System administrators should also implement network-level protections such as packet filtering rules that limit the size of TCP packets passing through monitored networks, effectively preventing the exploitation of this vulnerability. Network segmentation and monitoring of TCP packet sizes can help detect potential exploitation attempts. Additionally, implementing intrusion prevention systems that can identify and block malformed TCP packets is recommended. From an operational security perspective, organizations should conduct vulnerability assessments to identify all systems running vulnerable versions of libnids and ensure proper patch management protocols are in place. The ATT&CK framework categorizes this vulnerability under T1059, command and control, as exploitation could lead to remote code execution, and T1566, credential access, through potential privilege escalation opportunities that may arise from system compromise. Regular security audits and network traffic monitoring should be implemented to detect any exploitation attempts or anomalous packet behavior that could indicate this vulnerability is being targeted.