CVE-2018-17974 in tcpreplay
Summary
by MITRE
An issue was discovered in Tcpreplay 4.3.0 beta1. A heap-based buffer over-read was triggered in the function dlt_en10mb_encode() of the file plugins/dlt_en10mb/en10mb.c, due to inappropriate values in the function memmove(). The length (pktlen + ctx -> l2len) can be larger than source value (packet + ctx->l2len) because the function fails to ensure the length of a packet is valid. This leads to Denial of Service.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-17974 represents a critical heap-based buffer over-read flaw within Tcpreplay version 4.3.0 beta1, specifically within the dlt_en10mb_encode() function located in plugins/dlt_en10mb/en10mb.c. This issue arises from inadequate input validation mechanisms that fail to properly verify packet length parameters before memory operations are executed. The flaw manifests when the function memmove() processes a length parameter that exceeds the bounds of the source buffer, creating a scenario where memory is accessed beyond its allocated boundaries. The root cause stems from the improper handling of packet length calculations where pktlen + ctx->l2len can surpass the actual packet data size, leading to unpredictable memory access patterns that compromise system stability.
The technical implementation of this vulnerability demonstrates a classic buffer over-read condition that aligns with CWE-125, which describes out-of-bounds read vulnerabilities where an application reads memory beyond the boundaries of a buffer. The flaw occurs during the packet processing pipeline when Tcpreplay attempts to encode Ethernet frames, specifically when handling the layer 2 header information. The function fails to validate that the calculated packet length does not exceed the actual packet data available, creating a scenario where memmove() attempts to copy data from memory locations that may contain sensitive information or may be unmapped. This improper validation creates a path for attackers to craft malicious packet sequences that trigger the over-read condition, potentially exposing system memory contents or causing application instability.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a potential vector for more sophisticated attacks within network traffic analysis environments. When exploited, the heap-based buffer over-read can cause Tcpreplay to crash or terminate unexpectedly, disrupting network monitoring and analysis operations that depend on this tool for packet replay functionality. The vulnerability affects systems that utilize Tcpreplay for network protocol analysis, packet capture replay, or network testing scenarios where malformed packet data might be processed. Given that Tcpreplay is commonly used in security research, network debugging, and penetration testing environments, the impact extends to organizations that rely on this tool for network infrastructure validation and security assessments.
Mitigation strategies for CVE-2018-17974 should prioritize immediate patch deployment to the latest stable version of Tcpreplay where the buffer validation logic has been corrected. System administrators should implement input validation controls that verify packet length parameters before memory operations are executed, ensuring that the calculated packet size does not exceed the actual data available. The fix should incorporate bounds checking mechanisms that validate pktlen + ctx->l2len against the actual packet buffer size, preventing the memmove() function from accessing invalid memory regions. Organizations should also consider implementing network traffic filtering rules that prevent malformed packet data from reaching systems running Tcpreplay, while monitoring for unusual process behavior that might indicate exploitation attempts. This vulnerability demonstrates the importance of proper memory management practices and input validation in network security tools, aligning with ATT&CK technique T1059.007 for execution through command and scripting interpreter and T1499.004 for network disruption through denial of service attacks.