CVE-2017-3144 in DHCP
Summary
by MITRE
A vulnerability stemming from failure to properly clean up closed OMAPI connections can lead to exhaustion of the pool of socket descriptors available to the DHCP server. Affects ISC DHCP 4.1.0 to 4.1-ESV-R15, 4.2.0 to 4.2.8, 4.3.0 to 4.3.6. Older versions may also be affected but are well beyond their end-of-life (EOL). Releases prior to 4.1.0 have not been tested.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2017-3144 represents a critical resource exhaustion flaw within the Internet Systems Consortium DHCP (ISC DHCP) server implementations. This issue specifically targets the OMAPI (Open Management API) functionality which is used for remote management and configuration of DHCP servers. The vulnerability manifests when the DHCP server fails to properly clean up socket descriptors associated with closed OMAPI connections, creating a persistent resource leak that can ultimately lead to complete service denial. The affected versions span multiple release branches including 4.1.0 through 4.1-ESV-R15, 4.2.0 through 4.2.8, and 4.3.0 through 4.3.6, indicating this was a widespread issue affecting the core DHCP functionality that many network infrastructures depend upon. The vulnerability is particularly concerning because it operates at the fundamental level of socket management within the server's network handling capabilities, making it an attractive target for attackers seeking to disrupt network services.
The technical root cause of this vulnerability aligns with CWE-404, which describes improper resource cleanup or release, and more specifically relates to CWE-772, which covers resource leak vulnerabilities. The flaw occurs within the OMAPI connection handling code where socket descriptors are not properly closed and removed from the server's connection pool when OMAPI sessions terminate. This creates a gradual accumulation of unused socket descriptors that eventually exhaust the system's available file descriptor limits, effectively preventing the DHCP server from accepting new connections or managing existing ones. The mechanism works by maintaining a pool of available socket descriptors for handling OMAPI communications, but when connections close without proper cleanup, these descriptors remain allocated and unusable, leading to a progressive degradation of the server's ability to handle network traffic.
From an operational impact perspective, this vulnerability can result in complete denial of service for DHCP services within affected networks, potentially disrupting all network clients that rely on dynamic IP address assignment. The attack vector is relatively straightforward as it requires only sustained connection attempts to the OMAPI interface, which is typically exposed to network traffic in many deployments. Network administrators may observe gradual performance degradation before complete service failure, as the system slowly consumes available file descriptors until no new connections can be established. This vulnerability is particularly dangerous in enterprise environments where DHCP servers handle thousands of concurrent connections and where the OMAPI interface is actively used for automated configuration management. The impact extends beyond simple service disruption to potentially affecting network availability and business continuity, especially in environments where DHCP is critical for network operations.
Mitigation strategies for CVE-2017-3144 should prioritize immediate patching of affected ISC DHCP server versions to the latest stable releases that contain the necessary code fixes for proper OMAPI connection cleanup. Organizations should also implement monitoring solutions to track file descriptor usage on DHCP servers and establish alerting mechanisms for when descriptor pools approach critical thresholds. Network segmentation and access control measures should be enforced to limit exposure of the OMAPI interface to only authorized management systems, reducing the attack surface. Additionally, implementing connection timeouts and limiting concurrent OMAPI connections can help prevent exploitation by limiting the duration and frequency of potentially malicious connection attempts. The remediation process should include thorough testing of patched systems in controlled environments before deployment to production networks, ensuring that the fixes do not introduce compatibility issues with existing network management workflows that depend on OMAPI functionality. Security teams should also conduct vulnerability assessments to identify systems running unsupported versions of ISC DHCP that may be vulnerable despite not being explicitly listed in the affected ranges.