CVE-2011-0996 in dhcpcd
Summary
by MITRE
dhcpcd before 5.2.12 allows remote attackers to execute arbitrary commands via shell metacharacters in a hostname obtained from a DHCP message.
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Analysis
by VulDB Data Team • 02/02/2025
The vulnerability identified as CVE-2011-0996 affects dhcpcd versions prior to 5212, representing a critical command injection flaw in the Dynamic Host Configuration Protocol client implementation. This vulnerability arises from insufficient input sanitization when processing hostname information received from DHCP servers, creating an avenue for remote attackers to execute arbitrary commands on affected systems. The flaw specifically manifests when the dhcpcd utility processes hostname data obtained through DHCP messages without properly escaping or validating shell metacharacters that may be present in the received hostname field.
The technical exploitation of this vulnerability leverages the inherent trust placed in DHCP server responses by dhcpcd clients, allowing attackers to inject malicious shell commands through crafted hostname values. When the dhcpcd utility incorporates the malicious hostname into system commands without proper sanitization, it creates a command injection scenario where attacker-controlled input can be interpreted and executed by the underlying shell. This type of vulnerability falls under the CWE-78 category of Improper Neutralization of Special Elements used in OS Commands, which is a well-documented weakness in software systems that handle external input through shell operations.
The operational impact of CVE-2011-0996 extends beyond simple command execution, as it can enable attackers to gain full control of affected systems. Remote attackers can leverage this vulnerability to execute arbitrary code with the privileges of the dhcpcd process, potentially leading to complete system compromise. The attack vector is particularly concerning because it requires no authentication and can be initiated from any network location where the attacker can influence DHCP responses. This vulnerability directly aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically targeting the use of shell commands to execute malicious payloads. The vulnerability affects systems that rely on dhcpcd for network configuration and can be exploited in various network environments including corporate networks, public Wi-Fi, and cloud infrastructures where DHCP services are prevalent.
Mitigation strategies for CVE-2011-0996 primarily focus on updating to dhcpcd version 5212 or later, which includes proper input validation and sanitization of hostname data. Organizations should implement network segmentation and DHCP server hardening measures to limit the attack surface, including restricting DHCP server access to trusted network segments. Additionally, monitoring network traffic for suspicious DHCP responses and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability demonstrates the importance of input validation in network utilities and highlights the need for security-conscious development practices in system-level components that interact with external network protocols. Security teams should also consider implementing network access controls and firewall rules to prevent unauthorized DHCP server access, as this vulnerability can be exploited through man-in-the-middle attacks or compromised DHCP servers.