CVE-2020-3272 in Prime Network Registrar
Summary
by MITRE
A vulnerability in the DHCP server of Cisco Prime Network Registrar could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient input validation of incoming DHCP traffic. An attacker could exploit this vulnerability by sending a crafted DHCP request to an affected device. A successful exploit could allow the attacker to cause a restart of the DHCP server process, causing a DoS condition.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/19/2020
The vulnerability identified as CVE-2020-3272 resides within Cisco Prime Network Registrar's DHCP server implementation, representing a critical security flaw that undermines the availability of network infrastructure services. This device serves as a central DHCP server solution for enterprise networks, managing dynamic IP address allocation and network configuration for numerous devices. The vulnerability specifically targets the input validation mechanisms that process incoming DHCP requests, creating a pathway for malicious actors to disrupt essential network services without requiring authentication credentials.
The technical exploitation of this vulnerability stems from inadequate validation of DHCP packet contents, particularly in how the system processes malformed or crafted DHCP requests. When an attacker sends specially constructed DHCP messages to the affected Cisco Prime Network Registrar, the system fails to properly sanitize incoming data before processing. This insufficient input validation allows malicious packets to trigger unexpected behavior within the DHCP server process, ultimately leading to service disruption. The flaw operates at the protocol level where DHCP servers typically expect standardized packet structures, but the vulnerable implementation does not adequately verify packet integrity or enforce proper message boundaries.
Operationally, this vulnerability presents a significant risk to enterprise network availability and business continuity. A successful exploitation results in a complete denial of service condition where the DHCP server process restarts, effectively removing IP address assignment capabilities for the network. Network devices attempting to obtain or renew IP addresses would experience connection failures, potentially affecting hundreds or thousands of devices simultaneously. The remote nature of the attack means that adversaries can exploit this weakness from outside the network perimeter, making it particularly dangerous for organizations that expose their DHCP servers to external traffic. This vulnerability directly impacts the CIA triad's availability component, potentially causing cascading failures throughout dependent network services.
Security professionals should implement immediate mitigations including network segmentation to isolate the affected DHCP server from untrusted networks, deployment of access control lists to restrict DHCP traffic sources, and regular monitoring for anomalous DHCP request patterns. Organizations must also consider applying Cisco's official security patches and updates as released through their vulnerability management processes. The vulnerability aligns with CWE-20, which describes improper input validation, and maps to ATT&CK technique T1499.004 for network disruption attacks. Network administrators should establish baseline monitoring for DHCP server restart events and implement intrusion detection systems capable of identifying malformed DHCP traffic patterns. Additionally, the principle of least privilege should be enforced by limiting the exposure of DHCP services to only necessary network segments while maintaining comprehensive logging of all DHCP server activities for forensic analysis purposes.