CVE-2018-0309 in NX-OS
Summary
by MITRE
A vulnerability in the implementation of a specific CLI command and the associated Simple Network Management Protocol (SNMP) MIB for Cisco NX-OS (in standalone NX-OS mode) on Cisco Nexus 3000 and 9000 Series Switches could allow an authenticated, remote attacker to exhaust system memory on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to the incorrect implementation of the CLI command, resulting in a failure to free all allocated memory upon completion. An attacker could exploit this vulnerability by authenticating to the affected device and repeatedly issuing a specific CLI command or sending a specific SNMP poll request for a specific Object Identifier (OID). A successful exploit could allow the attacker to cause the IP routing process to restart or to cause a device reset, resulting in a DoS condition. Cisco Bug IDs: CSCvf23136.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability described in CVE-2018-0309 represents a critical memory management flaw within Cisco NX-OS software running in standalone mode on Nexus 3000 and 9000 Series Switches. This issue stems from improper memory deallocation mechanisms within the command line interface implementation and associated SNMP Management Information Base (MIB) components. The flaw specifically affects the handling of certain CLI commands and SNMP polling operations, creating a persistent memory leak condition that can be exploited by authenticated remote attackers. The vulnerability's impact extends beyond simple resource consumption as it directly affects the stability and availability of core network services, making it particularly dangerous in production environments where network uptime is critical.
The technical root cause of this vulnerability lies in the failure to properly release allocated memory resources when processing specific CLI commands and SNMP MIB requests. According to CWE-401, this represents a classic memory leak condition where allocated memory is not correctly freed, leading to progressive memory consumption over time. The flaw manifests when an attacker authenticates to the device and repeatedly executes the affected CLI command or sends SNMP poll requests targeting specific Object Identifiers. This repeated exploitation causes the system's memory pool to gradually deplete until critical resources are exhausted, triggering system instability and potential process restarts. The vulnerability's implementation affects the IP routing process within the NX-OS environment, which is fundamental to network operations and packet forwarding functions.
From an operational perspective, this vulnerability creates a significant denial of service risk that can compromise network availability and reliability. The attack vector requires only authentication credentials, making it accessible to both internal and external threat actors who have gained legitimate access to the device. When successfully exploited, the vulnerability can cause the IP routing process to restart or trigger a complete device reset, effectively bringing network services down until manual intervention or system reboot occurs. This behavior aligns with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries target system resources to prevent legitimate use of network services. The impact extends beyond immediate service disruption to potentially affect network stability, as routing process restarts can cause temporary loss of connectivity and traffic disruption across the affected network segment.
Mitigation strategies for CVE-2018-0309 should focus on immediate patch deployment through official Cisco security advisories, as the vendor has addressed this specific memory management flaw in subsequent software releases. Network administrators should implement strict access controls and authentication mechanisms to limit who can execute CLI commands on affected devices, reducing the attack surface for potential exploitation. Monitoring systems should be configured to detect unusual patterns of CLI command execution or SNMP polling activity that could indicate attempted exploitation. Additionally, implementing memory monitoring and alerting capabilities can help detect the early stages of memory exhaustion before complete system failure occurs. Network segmentation and redundant path configurations should be considered to minimize the impact of potential DoS events on overall network operations. The vulnerability highlights the importance of proper memory management practices in network operating systems and underscores the need for thorough testing of command implementations, particularly those involving resource allocation and deallocation processes.