CVE-2011-2748 in DHCP
Summary
by MITRE
The server in ISC DHCP 3.x and 4.x before 4.2.2, 3.1-ESV before 3.1-ESV-R3, and 4.1-ESV before 4.1-ESV-R3 allows remote attackers to cause a denial of service (daemon exit) via a crafted DHCP packet.
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Analysis
by VulDB Data Team • 12/02/2024
The vulnerability identified as CVE-2011-2748 represents a critical denial of service flaw affecting ISC DHCP server implementations across multiple versions including 3.x and 4.x series before specific patch releases. This vulnerability resides within the server component of the DHCP daemon and demonstrates how malformed network packets can trigger catastrophic system failures. The issue stems from inadequate input validation mechanisms within the DHCP packet processing pipeline, creating an exploitable condition where remote attackers can craft specific DHCP packets to force the daemon to terminate unexpectedly. This flaw operates at the network protocol level and directly impacts the availability of network services that depend on DHCP functionality for IP address allocation and network configuration management.
The technical exploitation of this vulnerability occurs when an attacker sends specifically crafted DHCP packets to the target server, triggering an unhandled exception or memory corruption within the DHCP daemon's processing logic. The flaw likely involves buffer overflows, integer overflows, or improper validation of packet fields that cause the server process to crash or exit abruptly. According to CWE classification, this vulnerability maps to CWE-121, which describes heap-based buffer overflow conditions, or CWE-125, representing out-of-bounds read errors, both of which can lead to daemon termination when malformed data is processed. The attack vector requires only network access to the DHCP server port, typically UDP 67 and 68, making it particularly dangerous in network environments where DHCP services are exposed to untrusted networks or where attackers can position themselves between clients and servers.
The operational impact of CVE-2011-2748 extends far beyond simple service disruption, as DHCP servers form the backbone of network infrastructure configuration management. When the daemon exits due to this vulnerability, network clients lose the ability to obtain IP addresses dynamically, resulting in complete network partitioning or significant service degradation. This vulnerability directly maps to ATT&CK technique T1499.004, which describes network denial of service attacks targeting infrastructure services. Organizations relying on DHCP for network operations face potential cascading failures where the loss of DHCP functionality can impact authentication services, DNS resolution, and other network-dependent systems that depend on proper IP address allocation. The vulnerability particularly affects enterprise networks, cloud environments, and any infrastructure where DHCP servers are publicly accessible or exposed to potentially malicious network traffic.
Mitigation strategies for this vulnerability require immediate patching of affected ISC DHCP server versions to the recommended secure releases including 4.2.2 and respective ESV patches for older versions. Network segmentation and access control measures should be implemented to restrict direct access to DHCP server ports from untrusted networks, utilizing firewalls and access control lists to limit exposure. Additional protective measures include implementing DHCP snooping mechanisms, configuring rate limiting on DHCP packet processing, and establishing monitoring systems to detect unusual patterns of DHCP traffic that might indicate exploitation attempts. Organizations should also consider deploying redundant DHCP servers with proper failover mechanisms to minimize service impact during exploitation windows. The vulnerability demonstrates the importance of proper input validation and error handling in network services, emphasizing that all external inputs must be rigorously validated regardless of their source or expected format to prevent similar issues in future deployments.