CVE-2017-12986 in macOS
Summary
by MITRE
The IPv6 routing header parser in tcpdump before 4.9.2 has a buffer over-read in print-rt6.c:rt6_print().
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Analysis
by VulDB Data Team • 01/05/2023
The vulnerability identified as CVE-2017-12986 represents a critical buffer over-read flaw within the tcpdump network packet analysis tool affecting versions prior to 4.9.2. This issue specifically resides in the IPv6 routing header parser implementation, where the print-rt6.c source file contains a function named rt6_print() that fails to properly validate input data length before attempting to read from memory regions. The flaw occurs when tcpdump processes network packets containing malformed IPv6 routing headers, creating conditions where the parser attempts to access memory beyond the allocated buffer boundaries.
The technical implementation of this vulnerability stems from inadequate bounds checking within the rt6_print() function which handles the display of IPv6 routing headers in captured network traffic. When tcpdump encounters an IPv6 packet with a routing header, the parser assumes certain minimum data lengths and structures without proper validation of the actual packet content. This allows an attacker to craft malicious network packets containing specially constructed IPv6 routing headers that trigger memory access violations when processed by the vulnerable tcpdump version. The buffer over-read occurs because the parser reads data beyond the intended buffer limits, potentially exposing sensitive memory contents or causing application crashes.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it creates potential attack vectors for remote exploitation. When an attacker can successfully trigger this buffer over-read condition, the consequences include application instability leading to crashes and potential memory corruption. In network monitoring environments where tcpdump is commonly deployed for traffic analysis, this vulnerability could be exploited by adversaries to disrupt network operations or potentially escalate privileges if the application runs with elevated permissions. The vulnerability affects any system running vulnerable versions of tcpdump in network monitoring or forensic analysis roles.
Mitigation strategies for CVE-2017-12986 primarily focus on immediate version updates to tcpdump 4.9.2 or later releases which contain the patched rt6_print() function with proper bounds checking. System administrators should prioritize patching affected installations, particularly those in critical network monitoring infrastructure where tcpdump is deployed. Additionally, network administrators can implement packet filtering rules to limit exposure by blocking malformed IPv6 traffic or restricting access to systems running vulnerable tcpdump versions. The vulnerability aligns with CWE-129, which addresses improper validation of length of input buffers, and could potentially map to ATT&CK technique T1059 for execution through compromised network monitoring tools. Organizations should also consider implementing network segmentation and access controls to limit potential exploitation vectors while maintaining operational security monitoring capabilities.