CVE-2012-6699 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 read) via a crafted response.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 02/04/2019
The vulnerability identified as CVE-2012-6699 resides within the dhcpcd 3.x implementation and specifically targets the decode_search function located in the dhcp.c file. This flaw represents a classic out-of-bounds read condition that occurs when processing DHCP responses from remote servers. The issue manifests when a malicious DHCP server crafts a specially formatted response that triggers improper bounds checking within the decode_search function, leading to memory access violations that can ultimately result in system instability or complete service disruption.
From a technical perspective, the vulnerability stems from inadequate input validation and boundary checking mechanisms within the DHCP client's response parsing logic. When dhcpcd processes DHCP replies, it attempts to decode various search domain parameters contained within the response packets. The decode_search function fails to properly validate the length and structure of incoming data, allowing an attacker to provide malformed search domain information that exceeds expected buffer boundaries. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, specifically manifesting as an out-of-bounds read condition that can be exploited remotely.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially be leveraged to crash the dhcpcd process or cause memory corruption that might lead to more severe consequences. Network administrators running dhcpcd versions affected by this vulnerability face significant risk in environments where untrusted DHCP servers might be present, such as public networks or poorly secured corporate environments. The remote exploitation capability means that attackers do not need physical access to the target system, making this vulnerability particularly dangerous in networked environments where DHCP services are commonly used for automatic IP address assignment and configuration.
This vulnerability aligns with several ATT&CK framework techniques including T1059 Command and Scripting Interpreter and T1499 Endpoint Denial of Service, as it enables adversaries to disrupt network services and potentially gain further access through service disruption. The flaw represents a critical weakness in network infrastructure management, particularly in environments where automatic DHCP configuration is relied upon for network connectivity. Organizations using dhcpcd 3.x should immediately implement mitigations including updating to patched versions, implementing network segmentation to isolate DHCP traffic, and deploying monitoring solutions to detect anomalous DHCP responses that might indicate exploitation attempts. The vulnerability underscores the importance of proper input validation and bounds checking in network protocol implementations, particularly those handling untrusted network data from potentially malicious sources.