CVE-2017-12896 in macOS
Summary
by MITRE
The ISAKMP parser in tcpdump before 4.9.2 has a buffer over-read in print-isakmp.c:isakmp_rfc3948_print().
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Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-12896 represents a critical buffer over-read flaw within the ISAKMP parser component of tcpdump software version 4.9.1 and earlier. This issue manifests specifically in the print-isakmp.c source file at the isakmp_rfc3948_print() function, where improper input validation leads to memory access violations that can potentially be exploited by malicious actors. The vulnerability affects network packet analysis tools that process Internet Security Association and Key Management Protocol traffic, which is fundamental to VPN and IPsec communications. ISAKMP serves as the framework for key exchange and security association establishment in IPsec implementations, making this vulnerability particularly concerning for network security infrastructure. The buffer over-read condition occurs when tcpdump attempts to parse malformed ISAKMP messages, specifically those conforming to RFC 3948 standards for IPsec over UDP encapsulation. This parsing error creates a scenario where the application reads memory beyond the allocated buffer boundaries, potentially exposing sensitive data or enabling arbitrary code execution.
The technical exploitation of this vulnerability requires an attacker to craft specially malformed ISAKMP packets that trigger the buffer over-read condition during packet processing. When tcpdump encounters such malformed input, the isakmp_rfc3948_print() function fails to properly validate the packet structure before attempting to read data beyond the intended buffer limits. This behavior can lead to information disclosure through memory dumping, application crashes, or in more severe cases, potential remote code execution depending on the system architecture and memory layout. The vulnerability's impact is amplified in environments where tcpdump is used for network monitoring and security analysis, as these systems often process untrusted network traffic from multiple sources. Network security tools and intrusion detection systems that rely on tcpdump for packet analysis become vulnerable to denial of service attacks or information leakage when processing maliciously crafted ISAKMP traffic. The flaw essentially allows attackers to manipulate the parser's memory access patterns through carefully constructed packet payloads that exploit the lack of proper bounds checking.
From a cybersecurity perspective, this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations. The attack surface is particularly relevant to the MITRE ATT&CK framework's technique T1046, which involves network service scanning and reconnaissance activities that could leverage such buffer over-read vulnerabilities to gain additional information about network infrastructure. Organizations using tcpdump for security monitoring, network troubleshooting, or forensic analysis face significant risk exposure when systems are running vulnerable versions of the software. The vulnerability's exploitation potential extends beyond simple denial of service scenarios, as it could enable attackers to extract sensitive information from the application's memory space, potentially including encryption keys or session data that would compromise the security of IPsec communications. This makes the vulnerability particularly dangerous in enterprise environments where IPsec VPNs are extensively deployed for secure communications. The issue represents a fundamental flaw in input validation and memory management practices within the tcpdump codebase, highlighting the importance of proper bounds checking in network protocol parsers.
Mitigation strategies for CVE-2017-12896 primarily involve upgrading to tcpdump version 4.9.2 or later, which contains the necessary patches to address the buffer over-read condition in the ISAKMP parser. System administrators should implement immediate patch management procedures to ensure all network monitoring systems are updated with the latest security fixes. Network segmentation and access controls should be strengthened to limit exposure to potentially malicious network traffic, particularly in environments where tcpdump is used for packet capture and analysis. Additional protective measures include implementing network monitoring solutions that can detect and filter anomalous ISAKMP traffic patterns, as well as conducting regular security assessments to identify systems running vulnerable versions of tcpdump. Organizations should also consider deploying intrusion prevention systems that can detect and block malformed ISAKMP packets that may be attempting to exploit this vulnerability. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date network security tools and implementing robust input validation practices in protocol parsing components. Regular vulnerability assessments and security audits should be conducted to identify similar buffer over-read conditions in other network analysis tools and security infrastructure components.