CVE-2017-13044 in macOS
Summary
by MITRE
The HNCP parser in tcpdump before 4.9.2 has a buffer over-read in print-hncp.c:dhcpv4_print().
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Analysis
by VulDB Data Team • 09/09/2024
The vulnerability identified as CVE-2017-13044 represents a critical buffer over-read flaw within the HNCP (Host Name Configuration Protocol) parser implementation of tcpdump software version 4.9.1 and earlier. This issue specifically manifests in the print-hncp.c source file at the dhcpv4_print() function, where improper input validation and boundary checking mechanisms fail to prevent excessive data reading beyond allocated memory buffers. The flaw occurs when tcpdump processes network packets containing HNCP data structures, particularly those related to DHCPv4 protocol implementations, creating a scenario where the parser attempts to read memory locations beyond the intended data boundaries.
The technical execution of this vulnerability involves the manipulation of network packet payloads that contain malformed HNCP structures, specifically those that trigger the dhcpv4_print() function during packet analysis. When tcpdump encounters such malformed data, the parser does not properly validate the length of incoming data structures before attempting to read them, leading to a buffer over-read condition. This condition can cause the application to access memory beyond its allocated buffer space, potentially reading sensitive data from adjacent memory locations or causing application instability. The vulnerability falls under CWE-125, which specifically addresses out-of-bounds read conditions, and represents a classic example of insufficient boundary checking in network protocol parsing implementations.
From an operational perspective, this vulnerability poses significant risks to network monitoring and security analysis systems that rely on tcpdump for packet inspection. Attackers can exploit this flaw by crafting malicious network packets containing specifically formatted HNCP data that triggers the buffer over-read condition when processed by vulnerable tcpdump versions. The impact extends beyond simple application crashes, as the over-read behavior could potentially expose sensitive information stored in adjacent memory regions, including authentication credentials, system configuration data, or other confidential information. This vulnerability directly maps to ATT&CK technique T1046, which involves the use of network service scanning and reconnaissance activities that can be amplified through protocol parsing vulnerabilities.
The mitigation strategies for CVE-2017-13044 primarily focus on immediate software updates to tcpdump version 4.9.2 or later, which includes the patched dhcpv4_print() function with proper boundary validation. Network administrators should also implement additional defensive measures such as network segmentation, access control lists, and monitoring for suspicious packet patterns that might indicate exploitation attempts. Organizations using tcpdump in critical security monitoring roles should conduct thorough vulnerability assessments of their network infrastructure to identify systems running vulnerable versions and ensure timely patch deployment. The fix implemented in the patched version addresses the root cause by introducing proper input validation and buffer length checking mechanisms that prevent the parser from reading beyond allocated memory boundaries, thereby eliminating the over-read condition that could be exploited by malicious actors.