CVE-2017-13034 in macOS
Summary
by MITRE
The PGM parser in tcpdump before 4.9.2 has a buffer over-read in print-pgm.c:pgm_print().
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Analysis
by VulDB Data Team • 12/05/2025
The vulnerability identified as CVE-2017-13034 represents a critical buffer over-read flaw within the Packet Generator Message (PGM) parser implementation of tcpdump software version 4.9.1 and earlier. This issue resides specifically within the print-pgm.c source file at the pgm_print() function, where improper bounds checking allows maliciously crafted PGM packets to trigger memory access violations. The vulnerability manifests when tcpdump processes network traffic containing PGM protocol data, particularly affecting systems that utilize tcpdump for network monitoring and packet analysis operations. The buffer over-read condition occurs because the parser does not adequately validate the length of incoming PGM message headers before attempting to read data from memory locations beyond the allocated buffer boundaries. This flaw enables attackers to craft specially formatted PGM packets that can cause tcpdump to access invalid memory regions, potentially leading to application crashes or, in more severe scenarios, arbitrary code execution.
The technical implementation of this vulnerability stems from inadequate input validation within the PGM packet parsing logic. When tcpdump encounters a PGM message, the pgm_print() function attempts to parse various header fields without sufficient verification of the actual message length against the available buffer space. This deficiency creates a scenario where an attacker can construct a PGM packet with a malformed header that specifies a length exceeding the actual data available in the packet buffer. The parser then proceeds to read beyond the legitimate buffer boundaries, accessing memory locations that may contain sensitive data or cause the application to terminate abnormally. This type of vulnerability falls under the CWE-129 weakness category, which encompasses issues related to improper validation of the length of input data, and more specifically aligns with CWE-125, which addresses buffer over-read conditions. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1059.007, where adversaries may exploit memory corruption vulnerabilities to execute arbitrary code or cause system instability through crafted network traffic.
The operational impact of CVE-2017-13034 extends beyond simple application crashes, potentially compromising network monitoring infrastructure and enabling denial-of-service attacks against systems relying on tcpdump for network analysis. Network administrators who deploy tcpdump for security monitoring, intrusion detection, or network troubleshooting may find their systems vulnerable to exploitation by attackers who can craft malicious PGM packets to disrupt network operations or gain unauthorized access to monitoring systems. The vulnerability affects any system running tcpdump versions prior to 4.9.2, including various Linux distributions, Unix systems, and network security appliances that incorporate tcpdump as part of their monitoring stack. In environments where tcpdump is used for continuous network monitoring, the attack surface expands significantly as attackers can exploit this vulnerability through network traffic without requiring direct system access. The buffer over-read condition could potentially expose sensitive information stored in memory adjacent to the affected buffer, making it a target for information disclosure attacks that align with ATT&CK technique T1005, which covers data from local system storage.
Mitigation strategies for CVE-2017-13034 primarily focus on immediate software updates to tcpdump version 4.9.2 or later, which contains the necessary patches to address the buffer over-read condition in the PGM parser. System administrators should prioritize updating tcpdump installations across all network monitoring infrastructure, particularly in environments where the software processes untrusted network traffic from external sources. Additionally, implementing network segmentation and access controls can help limit the potential impact of exploitation by restricting access to systems running tcpdump to trusted network segments. Network administrators should also consider deploying intrusion detection systems that can identify and block malformed PGM packets before they reach tcpdump processing components. The vulnerability highlights the importance of input validation and bounds checking in network protocol parsers, and organizations should review their network monitoring tool configurations to ensure proper handling of edge cases in packet processing. Security teams should monitor for exploitation attempts through network traffic analysis and implement logging mechanisms to detect potential attacks targeting this vulnerability. The fix implemented in tcpdump 4.9.2 addresses the root cause by introducing proper bounds checking before any memory access operations within the pgm_print() function, ensuring that the parser validates the actual length of incoming PGM messages against available buffer space before attempting to read data from memory regions.