CVE-2012-3954 in DHCP
Summary
by MITRE
Multiple memory leaks in ISC DHCP 4.1.x and 4.2.x before 4.2.4-P1 and 4.1-ESV before 4.1-ESV-R6 allow remote attackers to cause a denial of service (memory consumption) by sending many requests.
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Analysis
by VulDB Data Team • 03/27/2021
The vulnerability identified as CVE-2012-3954 represents a critical memory management flaw in the Internet Systems Consortium DHCP (ISC DHCP) software versions 4.1.x and 4.2.x prior to specific patch releases. This issue affects both the standard releases and the Enhanced Security Version (ESV) branches, creating a widespread exposure across multiple deployment scenarios. The vulnerability manifests as multiple memory leaks that occur when the DHCP server processes numerous client requests, ultimately leading to excessive memory consumption and potential system instability.
The technical implementation of this vulnerability stems from inadequate memory deallocation mechanisms within the DHCP server's request processing loop. When remote attackers send a large volume of DHCP requests to the affected server, the software fails to properly release allocated memory blocks after processing each transaction. This memory leak occurs repeatedly with each request, causing the server's memory footprint to grow continuously until system resources are exhausted. The flaw operates at the application layer and leverages the inherent nature of DHCP protocol interactions where clients frequently request IP address assignments, renewals, and other network configuration parameters.
From an operational perspective, this vulnerability creates significant denial of service risks for network infrastructure administrators who rely on ISC DHCP servers for IP address management. The memory consumption grows progressively with each malicious request, potentially causing the server to become unresponsive or crash entirely. Network availability is compromised as legitimate clients may be unable to obtain IP addresses, leading to service disruption across the entire network segment. The vulnerability is particularly dangerous because it can be exploited with relatively simple tools that generate high volumes of DHCP requests, making it an attractive target for network-level attacks.
The impact of CVE-2012-3954 aligns with CWE-401, which specifically addresses improper deallocation of memory resources, and falls under the ATT&CK technique T1499.004 for Network Denial of Service. Organizations running affected ISC DHCP versions face potential business disruption and increased operational overhead as they must monitor and potentially restart services regularly. The vulnerability demonstrates how resource exhaustion attacks can be particularly effective against critical network services that handle high volumes of requests. Security teams should implement monitoring solutions to detect unusual memory consumption patterns and establish automated alerting for systems running vulnerable software versions.
Mitigation strategies for this vulnerability include immediate deployment of patches released by ISC, specifically versions 4.2.4-P1 for the 4.2.x branch and 4.1-ESV-R6 for the 4.1-ESV branch. Network administrators should also implement rate limiting mechanisms to restrict the number of DHCP requests that can be processed within a given time window, effectively limiting the impact of potential attacks. Additionally, monitoring solutions should be deployed to track memory usage patterns and alert administrators when abnormal consumption levels are detected. Regular vulnerability assessments and penetration testing should be conducted to identify similar memory management issues in other network infrastructure components. The remediation process should include comprehensive testing of patched systems to ensure that legitimate DHCP functionality remains intact while addressing the memory leak vulnerabilities.