CVE-2012-6698 in dhcpcd
Summary
by MITRE
The decode_search function in dhcp.c in dhcpcd 3.x allows remote DHCP servers to cause a denial of service (out-of-bounds write) via a crafted response.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 02/04/2019
The vulnerability identified as CVE-2012-6698 resides within the dhcpcd 3.x implementation of the decode_search function in the dhcp.c file, representing a critical security flaw that enables remote attackers to execute denial of service attacks through carefully crafted DHCP responses. This issue manifests as an out-of-bounds write condition that occurs when the DHCP client processes malformed responses from malicious DHCP servers on the network. The vulnerability specifically affects versions of dhcpcd 3.x where the decode_search function fails to properly validate input data received from DHCP servers during the network configuration process.
The technical exploitation of this vulnerability occurs when a remote DHCP server sends a maliciously crafted response that contains improperly formatted search domain information. The decode_search function in dhcp.c does not perform adequate bounds checking or input validation on the search domain data, allowing attackers to write data beyond the allocated memory buffer. This out-of-bounds write can overwrite adjacent memory locations, potentially corrupting critical program state information, leading to unpredictable behavior including application crashes, system instability, or complete denial of service for network clients relying on DHCP for configuration. The flaw represents a classic buffer overflow vulnerability that falls under the CWE-121 category of stack-based buffer overflow conditions.
From an operational perspective, this vulnerability poses significant risks to network infrastructure and client systems that utilize dhcpcd for DHCP client operations. Attackers can leverage this weakness by positioning themselves as rogue DHCP servers on the network, either through direct network access or by compromising existing DHCP infrastructure. Once exploited, the vulnerability can disrupt network connectivity for affected clients, forcing them to lose network access until the dhcpcd process is restarted or the system is rebooted. This type of denial of service attack can be particularly problematic in enterprise environments where network availability is critical, as it can affect multiple clients simultaneously if the rogue server is properly configured to target specific network segments.
The attack vector for CVE-2012-6698 aligns with the ATT&CK framework's network infiltration techniques, specifically targeting the network service availability aspect of the attack lifecycle. The vulnerability demonstrates the importance of input validation in network protocol implementations, as it highlights how seemingly benign network services can become attack vectors when proper bounds checking is not implemented. Organizations using dhcpcd 3.x should consider implementing network segmentation and DHCP server authentication mechanisms as additional defensive measures, while also ensuring that all systems are updated to patched versions of the software to prevent exploitation. This vulnerability also underscores the necessity of following secure coding practices such as those outlined in the OWASP Secure Coding Practices, particularly regarding buffer management and input validation in network-facing applications. The impact of this vulnerability extends beyond simple service disruption to potentially enabling more sophisticated attacks if combined with other exploitation techniques, making immediate remediation essential for network security posture maintenance.