CVE-2017-12898 in macOS
Summary
by MITRE
The NFS parser in tcpdump before 4.9.2 has a buffer over-read in print-nfs.c:interp_reply().
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Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-12898 represents a critical buffer over-read flaw within the Network File System (NFS) parser implementation of tcpdump utility version 4.9.1 and earlier. This issue resides specifically within the print-nfs.c source file at the interp_reply() function, which processes Network File System responses during packet capture analysis. The flaw manifests when tcpdump attempts to parse NFS reply packets, particularly those containing malformed or unexpected data structures that exceed the allocated buffer boundaries during protocol interpretation. This vulnerability falls under the CWE-125 vulnerability category, which specifically addresses out-of-bounds read conditions in software implementations. The security implications are significant as this over-read condition could potentially lead to information disclosure or system instability when processing maliciously crafted network traffic.
The technical execution of this vulnerability occurs during the normal operation of tcpdump when it encounters NFS reply packets that contain unexpected data formats or sizes. The interp_reply() function in tcpdump's NFS parser does not properly validate the length or structure of incoming NFS reply data before attempting to read from memory locations beyond the intended buffer boundaries. This improper bounds checking allows an attacker to craft NFS packets with specially formatted reply data that triggers the over-read condition. The flaw is particularly concerning because tcpdump is commonly used by network administrators and security professionals for packet analysis, making it a frequent target for exploitation in network monitoring and forensic analysis scenarios. The vulnerability could be exploited through network traffic interception or by crafting malicious NFS replies that would cause tcpdump to read beyond allocated memory regions, potentially exposing sensitive information from adjacent memory locations.
The operational impact of CVE-2017-12898 extends beyond simple information disclosure, as it represents a potential pathway for more sophisticated attacks within network monitoring environments. When exploited, this vulnerability could allow attackers to gain access to sensitive data residing in memory adjacent to the buffer, potentially including authentication credentials, system information, or other confidential data processed by tcpdump during packet analysis. The attack surface is particularly wide given that tcpdump is widely deployed across various network security tools and monitoring systems, making it a valuable target for adversaries seeking to compromise network analysis infrastructure. This vulnerability aligns with ATT&CK technique T1046 which involves the use of network service scanning to identify vulnerabilities in networked systems, and could also facilitate subsequent techniques such as T1059 for command execution if the compromised tcpdump process is used in automated security tools or scripts. The exploitability of this vulnerability is heightened in environments where tcpdump is run with elevated privileges or in automated security monitoring contexts where it processes untrusted network traffic.
Mitigation strategies for CVE-2017-12898 primarily focus on immediate software updates and operational security measures. The most effective remediation is upgrading tcpdump to version 4.9.2 or later, which includes proper bounds checking in the NFS parser implementation to prevent the over-read condition. Organizations should also implement network segmentation and access controls to limit exposure of systems running tcpdump to untrusted network traffic. Additional mitigations include configuring tcpdump to operate with reduced privileges, implementing network intrusion detection systems to monitor for malicious NFS traffic patterns, and conducting regular vulnerability assessments of network monitoring tools. Security teams should also consider implementing network traffic filtering rules to limit NFS traffic exposure and establish monitoring procedures to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and bounds checking in network protocol parsers, reinforcing industry best practices outlined in standards such as the OWASP Secure Coding Practices and NIST SP 800-160 for secure software development lifecycle implementation.