CVE-2018-19325 in tcpdump
Summary
by MITRE
tcpdump 4.9.2 (and probably lower versions) is prone to a heap-based buffer over-read in the EXTRACT_32BITS function (extract.h, called from the rx_cache_find function, print-rx.c) due to improper serviceId sanitization.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/17/2020
The vulnerability identified as CVE-2018-19325 affects tcpdump version 4.9.2 and potentially earlier releases, representing a critical heap-based buffer over-read condition that compromises the integrity of network packet analysis tools. This flaw manifests within the EXTRACT_32BITS function located in the extract.h header file, which is invoked by the rx_cache_find function in print-rx.c module. The vulnerability stems from inadequate sanitization of the serviceId parameter, creating a scenario where maliciously crafted network packets can trigger unauthorized memory access patterns that exceed the bounds of allocated heap buffers.
The technical exploitation of this vulnerability occurs when tcpdump processes network traffic containing specially crafted packets that manipulate the serviceId field within the RX protocol structure. The EXTRACT_32BITS macro, designed to extract 32-bit values from byte streams, fails to validate input boundaries before performing memory operations. This improper validation allows attackers to manipulate the extraction process such that memory locations beyond the intended buffer boundaries are accessed, potentially leading to information disclosure, application crashes, or in severe cases, remote code execution depending on memory layout and system configuration. The vulnerability falls under CWE-125, which specifically addresses out-of-bounds read conditions, and represents a classic example of improper input validation in network protocol parsing components.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios, as it can enable attackers to extract sensitive information from the tcpdump process memory space. When exploited, the heap-based buffer over-read can potentially expose stack canaries, return addresses, or other critical memory contents that could aid in further exploitation attempts. Network administrators using tcpdump for security monitoring, intrusion detection, or forensic analysis face significant risk, as attackers could leverage this vulnerability to compromise the integrity of network traffic analysis tools that are critical for security operations. The vulnerability particularly affects systems where tcpdump is used in security-critical environments such as network monitoring appliances, security information and event management systems, and forensic analysis workstations.
Mitigation strategies for CVE-2018-19325 should prioritize immediate patching of tcpdump installations to versions that address the buffer over-read condition in the EXTRACT_32BITS function. Organizations should implement network segmentation and access controls to limit exposure of systems running tcpdump to untrusted network traffic. Additionally, deploying network intrusion detection systems that can identify and block malformed RX protocol packets can provide layered defense against exploitation attempts. The vulnerability demonstrates the importance of proper input validation in protocol parsing libraries and aligns with ATT&CK technique T1059.007 for execution through network protocols, highlighting how seemingly benign network analysis tools can become attack vectors when proper security controls are not implemented. Regular security assessments and vulnerability scanning should include verification of tcpdump versions and proper implementation of input sanitization measures to prevent similar issues in other network protocol parsing components.