CVE-2020-18976 in tcpreplay
Summary
by MITRE • 08/25/2021
Buffer Overflow in Tcpreplay v4.3.2 allows attackers to cause a Denial of Service via the 'do_checksum' function in 'checksum.c'. It can be triggered by sending a crafted pcap file to the 'tcpreplay-edit' binary. This issue is different than CVE-2019-8381.
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Analysis
by VulDB Data Team • 08/29/2021
The vulnerability identified as CVE-2020-18976 represents a critical buffer overflow condition within the Tcpreplay v4.3.2 network packet manipulation tool suite. This flaw specifically manifests within the 'do_checksum' function located in the 'checksum.c' source file, creating a potential attack vector that can be exploited to induce denial of service conditions. The vulnerability is particularly concerning because it affects the tcpreplay-edit binary component, which serves as a crucial tool for modifying and replaying network packet captures stored in pcap format. Attackers can trigger this vulnerability by crafting malicious pcap files that, when processed by the tcpreplay-edit utility, cause the application to crash or become unresponsive.
The technical nature of this buffer overflow stems from improper input validation and memory management within the checksum calculation routine. When the 'do_checksum' function processes packet data from a crafted pcap file, it fails to adequately verify the boundaries of buffer allocations, leading to memory corruption that can result in arbitrary code execution or complete application termination. This vulnerability operates at the intersection of network security and software engineering, where the manipulation of packet data structures directly impacts the stability and reliability of network analysis tools. The flaw specifically demonstrates poor defensive programming practices that violate fundamental security principles, as highlighted by CWE-121 which addresses stack-based buffer overflow conditions, and CWE-125 which covers out-of-bounds read vulnerabilities.
From an operational perspective, this vulnerability poses significant risks to network security professionals who rely on Tcpreplay for packet analysis, testing, and replay operations. The attack scenario involves an adversary sending specially crafted pcap files to systems running tcpreplay-edit, which can lead to service disruption and potential data loss during critical network monitoring or penetration testing activities. The impact extends beyond simple denial of service, as the vulnerability can be leveraged to compromise the integrity of network analysis workflows, potentially causing security teams to miss critical network events or to waste resources on investigating false positives. Organizations using tcpreplay for security testing, network performance analysis, or packet capture manipulation face substantial risk if this vulnerability remains unpatched, as it represents a potential entry point for adversaries seeking to disrupt network operations or establish persistent access through compromised analysis tools.
The mitigation strategy for CVE-2020-18976 requires immediate patching of affected Tcpreplay installations to version 4.3.3 or later, which contains the necessary code modifications to prevent the buffer overflow condition. Network administrators should also implement defensive measures such as validating and sanitizing all pcap files before processing them through tcpreplay-edit, particularly those received from untrusted sources. Additionally, organizations should consider implementing network segmentation and access controls to limit exposure of systems running tcpreplay utilities, as recommended by the MITRE ATT&CK framework for network security operations. The vulnerability underscores the importance of maintaining up-to-date network security tools and implementing robust input validation mechanisms to prevent similar issues in other network analysis software components. Security teams should also conduct regular vulnerability assessments of their network toolchains to identify and remediate similar buffer overflow conditions that could potentially compromise network infrastructure integrity and operational continuity.