CVE-2018-0456 in NX-OS
Summary
by MITRE
A vulnerability in the Simple Network Management Protocol (SNMP) input packet processor of Cisco NX-OS Software could allow an authenticated, remote attacker to cause the SNMP application of an affected device to restart unexpectedly. The vulnerability is due to improper validation of SNMP protocol data units (PDUs) in SNMP packets. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device. A successful exploit could allow the attacker to cause the SNMP application to restart multiple times, leading to a system-level restart and a denial of service (DoS) condition.
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Analysis
by VulDB Data Team • 05/30/2023
The vulnerability identified as CVE-2018-0456 represents a critical flaw in Cisco NX-OS Software's SNMP implementation that demonstrates the inherent risks associated with protocol processing errors in network infrastructure devices. This issue specifically targets the Simple Network Management Protocol input packet processor, which serves as a fundamental component for network monitoring and management operations across Cisco enterprise networks. The vulnerability stems from insufficient validation mechanisms within the SNMP protocol data units (PDUs) processing pipeline, creating a pathway for malicious actors to manipulate the system's operational state through carefully crafted network traffic.
The technical exploitation of this vulnerability occurs through the manipulation of SNMP packets that contain malformed PDUs, which the affected Cisco NX-OS devices fail to properly validate before processing. When an authenticated remote attacker successfully crafts and transmits these malicious SNMP packets, the system's SNMP application undergoes unexpected restart cycles that can cascade into complete system-level reboots. This behavior directly violates the expected reliability and stability requirements for network infrastructure devices, as the vulnerability allows for repeated triggering of service disruption events that can be used to maintain persistent denial of service conditions against critical network management functions.
From an operational impact perspective, this vulnerability creates significant risk for enterprise network environments where SNMP monitoring is extensively utilized for system health tracking, performance metrics collection, and automated network management operations. The DoS condition resulting from repeated SNMP application restarts effectively renders the affected device's management capabilities unavailable, potentially disrupting network monitoring systems, automated response mechanisms, and critical infrastructure management functions. Network administrators may experience complete loss of visibility into affected devices, forcing manual intervention and potentially impacting business continuity operations that depend on consistent network monitoring and management capabilities.
The vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and demonstrates characteristics consistent with ATT&CK technique T1499.004, specifically the use of network denial of service attacks against network infrastructure. Organizations should implement immediate mitigations including applying the relevant Cisco security patches, implementing SNMP access controls through access control lists, and deploying network segmentation strategies to limit the scope of potential exploitation. Additionally, monitoring for unusual SNMP traffic patterns and implementing intrusion detection systems that can identify malformed SNMP PDUs will help detect potential exploitation attempts before they can cause significant operational disruption to network management functions and overall infrastructure stability.