CVE-2017-12987 in macOS
Summary
by MITRE
The IEEE 802.11 parser in tcpdump before 4.9.2 has a buffer over-read in print-802_11.c:parse_elements().
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Analysis
by VulDB Data Team • 01/05/2023
The vulnerability identified as CVE-2017-12987 represents a critical buffer over-read flaw within the IEEE 802.11 packet parsing functionality of tcpdump versions prior to 4.9.2. This issue resides in the print-802_11.c source file at the parse_elements() function, where the software fails to properly validate input data length before attempting to read from memory buffers. The flaw occurs during the processing of wireless network packets, specifically when tcpdump attempts to parse the element IDs and their associated data within 802.11 management frames. When encountering malformed or specially crafted wireless packets, the parser continues reading beyond the allocated buffer boundaries, potentially accessing invalid memory locations and causing unpredictable behavior.
This vulnerability falls under CWE-125, which specifically addresses out-of-bounds read conditions in software implementations. The issue demonstrates a classic buffer over-read pattern where the tcpdump application does not perform adequate bounds checking before processing variable-length data structures within 802.11 frames. The IEEE 802.11 standard defines various management frames with flexible element structures, where element IDs are followed by length fields that indicate how many bytes of data follow. When these length fields contain invalid or malicious values, the parser fails to validate them against the actual available data, leading to the over-read condition. The operational impact extends beyond simple application crashes, as this vulnerability could potentially be exploited to execute arbitrary code or cause denial of service in systems that rely on tcpdump for network monitoring and analysis.
The security implications of CVE-2017-12987 align with ATT&CK technique T1059.007, which covers the execution of malicious code through network-based tools. When exploited, this vulnerability could allow attackers to compromise systems running vulnerable versions of tcpdump, particularly those used in network security monitoring, intrusion detection systems, or forensic analysis environments. The flaw is particularly dangerous in network infrastructure monitoring contexts where tcpdump is commonly deployed to capture and analyze wireless traffic. Attackers could craft malicious 802.11 management frames with malformed element data that would trigger the buffer over-read when processed by the vulnerable tcpdump version, potentially leading to system instability or remote code execution.
Mitigation strategies for this vulnerability primarily involve upgrading to tcpdump version 4.9.2 or later, which contains the necessary patches to address the buffer over-read condition. System administrators should also implement network segmentation and monitoring to detect and prevent the injection of malformed wireless frames into monitored networks. Additional defensive measures include deploying network access control mechanisms that can filter out suspicious 802.11 frames and implementing proper input validation for all network packet parsing operations. The vulnerability demonstrates the importance of rigorous bounds checking in network protocol parsers and highlights the need for comprehensive testing of edge cases in wireless protocol implementations. Organizations should also consider implementing intrusion prevention systems that can detect and block malformed packets that attempt to exploit similar buffer over-read vulnerabilities in network monitoring tools.