CVE-2009-1892 in dhcp
Summary
by MITRE
dhcpd in ISC DHCP 3.0.4 and 3.1.1, when the dhcp-client-identifier and hardware ethernet configuration settings are both used, allows remote attackers to cause a denial of service (daemon crash) via unspecified requests.
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Analysis
by VulDB Data Team • 08/12/2021
The vulnerability identified as CVE-2009-1892 affects the ISC DHCP server versions 3.0.4 and 3.1.1, specifically when both dhcp-client-identifier and hardware ethernet configuration settings are simultaneously enabled. This flaw represents a denial of service condition that can be exploited remotely through unspecified requests, potentially causing the dhcpd daemon to crash and terminate its operations. The issue arises from improper handling of client identification parameters within the DHCP server's processing logic, creating a condition where malformed or specially crafted network requests can trigger unexpected behavior in the server's memory management or control flow.
The technical root cause of this vulnerability stems from inadequate input validation and error handling within the DHCP server's client identification processing subsystem. When both dhcp-client-identifier and hardware ethernet parameters are configured, the server's internal state management becomes inconsistent during request processing, leading to memory corruption or control flow exceptions that result in daemon termination. This type of vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap-based data structures. The flaw demonstrates characteristics of improper handling of resources and memory management issues that can lead to service interruption and system availability compromise.
From an operational perspective, this vulnerability presents significant risk to network infrastructure as it allows remote attackers to disrupt DHCP services without requiring authentication or privileged access. The impact extends beyond simple service disruption, potentially affecting network connectivity for all devices relying on the affected DHCP server for IP address allocation. Network administrators may experience service outages that can cascade through dependent systems, particularly in environments where DHCP serves as a critical component of network infrastructure. The vulnerability's remote exploitability means that attackers can target the service from outside the network perimeter, making it particularly dangerous for publicly accessible DHCP servers or those exposed through NAT configurations.
The attack surface for this vulnerability encompasses any network environment utilizing ISC DHCP server versions 3.0.4 or 3.1.1 with both dhcp-client-identifier and hardware ethernet configuration parameters enabled. This includes enterprise networks, ISP environments, and any organization relying on ISC DHCP for network address management. The vulnerability's exploitation requires minimal privileges and can be executed through standard network traffic, making it accessible to attackers with basic network reconnaissance capabilities. According to ATT&CK framework category T1499, this vulnerability represents a denial of service attack that can be classified under the technique of "Endpoint Denial of Service" where the attacker targets network services to prevent legitimate use of resources.
Mitigation strategies for CVE-2009-1892 should prioritize immediate patching of affected ISC DHCP server installations to versions that address the identified memory management and input validation issues. Organizations should also implement network segmentation to limit exposure of DHCP servers to untrusted networks and consider disabling unnecessary client identification parameters when not required for network operations. Monitoring systems should be configured to detect unusual DHCP traffic patterns or daemon restarts that may indicate exploitation attempts. Additionally, implementing redundant DHCP services and proper failover mechanisms can help maintain network availability during potential exploitation events, while network access controls can limit who can submit requests to the affected service. The vulnerability serves as a reminder of the critical importance of proper input validation and resource management in network services, particularly those handling dynamic client requests in mission-critical infrastructure environments.