CVE-2010-2156 in DHCP
Summary
by MITRE
ISC DHCP 4.1 before 4.1.1-P1 and 4.0 before 4.0.2-P1 allows remote attackers to cause a denial of service (server exit) via a zero-length client ID.
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Analysis
by VulDB Data Team • 01/25/2025
The vulnerability identified as CVE-2010-2156 affects ISC DHCP server versions prior to 4.1.1-P1 and 4.0.2-P1, representing a critical denial of service flaw that can be exploited by remote attackers to terminate the DHCP server process. This vulnerability specifically targets the handling of client identifiers within the DHCP protocol implementation, where the server fails to properly validate incoming client ID parameters. The flaw manifests when a malicious actor sends a DHCP request containing a zero-length client identifier, which causes the server to crash and exit unexpectedly. This type of vulnerability falls under the category of improper input validation as classified by CWE-20, where the system does not adequately check the length or format of input data before processing it. The impact of this vulnerability extends beyond simple service disruption as it can be leveraged to create persistent denial of service conditions that affect network infrastructure and potentially compromise network availability for legitimate users.
The technical exploitation of this vulnerability occurs at the protocol level where ISC DHCP server processes incoming DHCP requests without proper validation of the client identifier field. When the server encounters a zero-length client ID, it fails to handle this edge case gracefully and instead crashes the entire server process. This represents a classic buffer over-read or improper state handling issue that can be categorized under CWE-129 and CWE-20, as the server does not validate the bounds of the client identifier field before attempting to process it. The vulnerability demonstrates poor error handling practices and inadequate input sanitization mechanisms within the DHCP server implementation. Attackers can exploit this by crafting specially malformed DHCP packets that contain empty client ID fields, which when processed by the vulnerable server cause an immediate termination of the DHCP service. This type of attack aligns with the ATT&CK technique T1499.004 for network denial of service attacks and represents a fundamental flaw in the server's robustness against malformed input.
The operational impact of CVE-2010-2156 extends significantly beyond immediate service disruption, as DHCP servers form the backbone of network infrastructure management. When a DHCP server becomes unavailable due to this vulnerability, all devices relying on dynamic IP address assignment within that network segment will be unable to obtain network connectivity until the server is manually restarted or the vulnerability is patched. This can affect large enterprise networks, internet service providers, or any organization where DHCP services are critical to network operations. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication or special privileges, making it an attractive target for attackers seeking to disrupt network services. Network administrators may experience cascading failures as dependent services that rely on DHCP for IP address management also become compromised. Organizations using affected ISC DHCP versions are at risk of extended downtime and potential business disruption, especially in environments where network availability is critical for operations. The vulnerability also highlights the importance of proper software testing and validation of edge cases in network infrastructure components.
Mitigation strategies for CVE-2010-2156 focus primarily on updating to patched versions of ISC DHCP server software, specifically versions 4.1.1-P1 or 4.0.2-P1, which contain the necessary fixes to properly validate client identifier fields. Organizations should implement comprehensive patch management procedures to ensure all DHCP servers are updated promptly when security patches become available. Additionally, network administrators can implement monitoring solutions to detect anomalous DHCP traffic patterns that might indicate exploitation attempts, though this approach provides reactive rather than preventive protection. The vulnerability serves as a reminder of the critical importance of input validation and robust error handling in network infrastructure software, aligning with security best practices outlined in frameworks such as NIST SP 800-53 and ISO 27001. Network segmentation and firewall rules can provide additional protection by limiting access to DHCP servers, though these measures do not address the root cause. Organizations should also consider implementing redundant DHCP servers or failover mechanisms to maintain network availability in case of successful exploitation attempts. Regular security assessments and vulnerability scanning should include checks for this specific vulnerability to ensure comprehensive protection against similar flaws in network infrastructure components.