CVE-2018-0299 in NX-OS
Summary
by MITRE
A vulnerability in the Simple Network Management Protocol (SNMP) feature of Cisco NX-OS on the Cisco Nexus 4000 Series Switch could allow an authenticated, remote attacker to cause the device to unexpectedly reload, resulting in a denial of service (DoS) condition. The vulnerability is due to incomplete validation of an SNMP poll request for a specific MIB. An attacker could exploit this vulnerability by sending a specific SNMP poll request to the targeted device. An exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvg10442.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-0299 represents a critical denial of service weakness within Cisco NX-OS software running on Nexus 4000 Series switches. This flaw specifically impacts the Simple Network Management Protocol implementation, which is fundamental to network monitoring and management operations. The vulnerability stems from inadequate input validation mechanisms within the SNMP polling functionality, creating a pathway for malicious actors to disrupt network operations through deliberate device reloads. The affected device architecture processes SNMP requests without proper sanitization of MIB (Management Information Base) queries, allowing crafted payloads to trigger unexpected system behavior. Network administrators responsible for maintaining these critical infrastructure components must understand that this vulnerability directly compromises system availability and operational continuity.
The technical exploitation of this vulnerability occurs through specifically crafted SNMP poll requests targeting particular MIB objects within the affected software implementation. When an authenticated attacker submits a malformed SNMP query, the NX-OS software fails to properly validate the incoming request parameters, leading to a buffer overflow or memory corruption condition. This validation failure manifests as an unexpected system restart or reload event, effectively rendering the switch unavailable for network operations. The vulnerability's classification as incomplete validation aligns with CWE-20, which addresses "Improper Input Validation" in software systems. The specific nature of the flaw suggests that the SNMP processing module lacks proper boundary checks and parameter verification mechanisms, allowing malicious inputs to traverse normal execution paths and trigger system-level failures. Attackers leveraging this vulnerability can repeatedly exploit the condition to maintain persistent DoS attacks against targeted network infrastructure.
The operational impact of CVE-2018-0299 extends beyond simple service disruption, potentially affecting entire network segments dependent on the compromised switch. Network availability is severely compromised as the device enters an indefinite reload cycle, preventing legitimate management operations and disrupting data transmission flows. The vulnerability's remote exploitability means attackers do not require physical access or local network presence, enabling widespread disruption from external locations. This characteristic significantly increases the attack surface and makes the vulnerability particularly dangerous in production environments where network reliability is paramount. Organizations may experience cascading failures if multiple switches in a network segment are affected, leading to broader service outages. The DoS condition can persist until manual intervention occurs, requiring system administrators to perform device restarts and potentially reconfigure network topologies. From an operational security perspective, this vulnerability undermines the trustworthiness of network infrastructure and may trigger compliance violations in regulated environments.
Mitigation strategies for CVE-2018-0299 should prioritize immediate patch deployment through official Cisco security advisories, as the vendor has released specific fixes addressing the SNMP validation weakness. Network administrators must implement strict access controls to limit SNMP polling permissions, ensuring only authorized management systems can submit requests to affected devices. The principle of least privilege should be enforced by configuring SNMP communities with minimal required permissions and restricting access based on network location and authentication credentials. Network segmentation can help contain potential exploitation attempts by isolating vulnerable switches from critical network segments. Monitoring systems should be enhanced to detect unusual reload patterns or abnormal SNMP traffic volumes that may indicate exploitation attempts. The vulnerability's relationship to ATT&CK technique T1499.004, "Endpoint Denial of Service," demonstrates how this flaw can be leveraged as part of broader attack campaigns targeting network availability. Regular vulnerability assessments should include verification of SNMP configurations and monitoring for unauthorized access attempts to ensure comprehensive protection against this and similar threats.