CVE-2016-1504 in dhcpcd
Summary
by MITRE
dhcpcd before 6.10.0 allows remote attackers to cause a denial of service (invalid read and crash) via vectors related to the option length.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2016-1504 affects dhcpcd versions prior to 6.10.0 and represents a critical denial of service weakness that can be exploited by remote attackers. This issue stems from improper handling of DHCP option lengths within the dhcpcd client implementation, creating a scenario where maliciously crafted DHCP responses can trigger invalid memory reads and subsequent application crashes. The vulnerability specifically targets the DHCP client daemon that manages network configuration through dynamic host configuration protocol communications, making it a significant concern for network infrastructure security.
The technical flaw manifests when dhcpcd processes DHCP options with malformed or excessive length values in DHCP packets received from network servers. This improper validation allows attackers to craft DHCP responses containing options with invalid length fields that exceed expected boundaries or contain negative values. The client application fails to properly sanitize these inputs before processing, leading to memory access violations and ultimately causing the dhcpcd process to terminate unexpectedly. This behavior aligns with CWE-129, which describes improper validation of array indices, and CWE-125, which addresses out-of-bounds read conditions. The vulnerability operates at the network protocol level where DHCP client implementations must correctly parse and validate incoming configuration data.
The operational impact of CVE-2016-1504 extends beyond simple service disruption as it can compromise network connectivity for affected systems. When the dhcpcd daemon crashes, network clients lose their ability to automatically configure network parameters such as IP addresses, subnet masks, gateways, and DNS servers. This creates a cascading effect where devices may become unreachable or require manual network configuration, potentially affecting entire network segments if multiple clients are running vulnerable dhcpcd versions. The vulnerability is particularly dangerous in environments where automatic network configuration is critical for operations, such as enterprise networks, IoT deployments, or systems with limited administrative access.
From a threat modeling perspective, this vulnerability maps to several ATT&CK techniques including T1071.004 for application layer protocol communication and T1499.004 for network disruption. The attack vector requires only the ability to influence DHCP responses on the local network segment, making it relatively accessible to attackers who can perform DHCP spoofing or man-in-the-middle attacks. Organizations should implement network segmentation and DHCP server authentication mechanisms to mitigate exposure. The recommended mitigation strategy involves upgrading to dhcpcd version 6.10.0 or later, which includes proper input validation and bounds checking for DHCP option lengths. Additionally, network administrators should consider implementing DHCP snooping features and monitoring for unusual DHCP traffic patterns that might indicate exploitation attempts.
The vulnerability demonstrates the importance of robust input validation in network protocol implementations and highlights how seemingly minor parsing errors can lead to significant service disruption. It underscores the need for security-conscious development practices and thorough testing of network client applications against malformed inputs. Organizations maintaining systems with vulnerable dhcpcd versions should conduct immediate assessments of their network infrastructure and implement appropriate controls to prevent exploitation while planning for necessary software updates to address this persistent security weakness.