CVE-2017-12894 in macOS
Summary
by MITRE
Several protocol parsers in tcpdump before 4.9.2 could cause a buffer over-read in addrtoname.c:lookup_bytestring().
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-12894 represents a critical buffer over-read flaw affecting tcpdump versions prior to 4.9.2. This issue resides within the addrtoname.c file in the lookup_bytestring() function, which is responsible for converting network addresses into human-readable names during packet analysis operations. The flaw occurs when tcpdump processes malformed network packets that contain oversized or improperly formatted byte sequences, causing the application to read beyond the allocated memory boundaries. This type of vulnerability falls under the category of memory safety issues and can be classified as a CWE-125: Out-of-bounds Read according to the Common Weakness Enumeration standards. The vulnerability demonstrates how protocol parsing functions can become attack vectors when they fail to properly validate input data before processing.
The technical implementation of this vulnerability involves the tcpdump application's network protocol parsers that attempt to convert raw network data into meaningful address representations for display purposes. When processing packets with malformed byte sequences, the lookup_bytestring() function fails to properly bounds-check the data being read, leading to a situation where the application attempts to access memory locations beyond the intended buffer boundaries. This over-read behavior can result in the application reading sensitive data from adjacent memory locations, potentially exposing internal system information or causing application instability. The flaw is particularly concerning because tcpdump is widely used for network monitoring and security analysis, making it a common target for attackers seeking to exploit memory corruption vulnerabilities. This vulnerability aligns with ATT&CK technique T1059.007: Command and Scripting Interpreter: Python, as it demonstrates how network protocol parsing can be exploited to gain unauthorized access to system information through memory corruption.
The operational impact of CVE-2017-12894 extends beyond simple application crashes or instability, as it creates potential avenues for information disclosure and system compromise. When exploited, this vulnerability can allow attackers to extract sensitive data from memory locations adjacent to the vulnerable buffer, potentially exposing credentials, cryptographic keys, or other confidential information. The vulnerability affects tcpdump's ability to properly analyze network traffic, which can lead to false security assessments and missed threat detection opportunities. Organizations relying on tcpdump for network monitoring, intrusion detection, or security auditing may experience degraded operational capabilities when this vulnerability is present. The flaw particularly impacts environments where tcpdump is used in automated security monitoring systems, as any compromise of the tool's integrity can undermine the entire security infrastructure. The vulnerability also demonstrates the importance of proper input validation in network protocol parsers, as it highlights how seemingly benign packet data can be crafted to exploit memory safety issues. This vulnerability type is commonly associated with the broader category of buffer over-reads that can be leveraged for privilege escalation or information disclosure attacks, making it a significant concern for network security operations.
Mitigation strategies for CVE-2017-12894 focus primarily on updating tcpdump to version 4.9.2 or later, which includes proper bounds-checking mechanisms in the lookup_bytestring() function. System administrators should also implement network segmentation and access controls to limit exposure to potentially malicious network traffic that could trigger the vulnerability. Regular security assessments and vulnerability scanning should be conducted to identify systems running vulnerable versions of tcpdump. Additional protective measures include implementing network monitoring rules that can detect and block malformed packets that may trigger the vulnerability, as well as maintaining up-to-date security patches for all network analysis tools. Organizations should also consider implementing network traffic filtering at the perimeter to reduce the attack surface for such vulnerabilities. The fix implemented in tcpdump 4.9.2 demonstrates proper defensive programming practices that include bounds checking, input validation, and secure memory management techniques that align with industry best practices for preventing buffer over-read conditions. This vulnerability serves as a reminder of the critical importance of keeping network security tools updated and the potential consequences of running vulnerable software in production environments.