CVE-2020-3170 in NX-OS
Summary
by MITRE
A vulnerability in the NX-API feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause an NX-API system process to unexpectedly restart. The vulnerability is due to incorrect validation of the HTTP header of a request that is sent to the NX-API. An attacker could exploit this vulnerability by sending a crafted HTTP request to the NX-API on an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition in the NX-API service; however, the Cisco NX-OS device itself would still be available and passing network traffic. Note: The NX-API feature is disabled by default.
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Analysis
by VulDB Data Team • 04/06/2024
The vulnerability identified as CVE-2020-3170 resides within the NX-API feature of Cisco NX-OS Software, representing a significant security weakness that could be exploited by unauthenticated remote attackers. This flaw specifically targets the HTTP header validation mechanism within the NX-API system process, creating a pathway for malicious actors to disrupt service availability without compromising the underlying device functionality. The vulnerability's impact is classified as a denial of service condition that affects the NX-API service specifically, while maintaining the operational integrity of the broader network device. The NX-API feature remains disabled by default, which provides a baseline level of protection but does not eliminate the risk for devices where this functionality has been enabled.
The technical exploitation of this vulnerability occurs through the manipulation of HTTP headers in requests sent to the NX-API endpoint on affected Cisco devices. The flaw stems from insufficient validation of incoming HTTP header parameters, allowing attackers to craft malicious requests that trigger unexpected system process restarts. This improper input validation represents a classic security weakness that aligns with CWE-20, which encompasses "Improper Input Validation" as a fundamental software security flaw. The vulnerability demonstrates how inadequate header sanitization can lead to process-level disruptions, even when the core device remains functional and continues to forward network traffic.
The operational impact of this vulnerability extends beyond simple service disruption, as it creates potential for unauthorized system interference that could be leveraged in broader attack scenarios. While the Cisco NX-OS device continues to operate normally and pass network traffic, the NX-API service becomes unavailable, potentially affecting management operations, monitoring capabilities, and automated network control functions. This type of denial of service attack aligns with ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" and represents a method that attackers might use to degrade system functionality without achieving full system compromise. The vulnerability's exploitation does not require authentication credentials, making it particularly dangerous as it can be executed by any remote attacker with network access to the affected device.
Mitigation strategies for CVE-2020-3170 should prioritize the immediate disabling of the NX-API feature on all affected devices unless absolutely necessary for operational requirements. Network administrators should implement network segmentation to limit access to NX-API endpoints and consider deploying additional monitoring solutions to detect anomalous HTTP header patterns that might indicate exploitation attempts. Cisco has released patches and updates to address this vulnerability, and organizations should ensure their devices are running patched software versions. The implementation of web application firewalls and intrusion detection systems can provide additional layers of protection by monitoring and filtering suspicious HTTP requests targeting the NX-API service. Regular vulnerability assessments and security audits should be conducted to identify any devices with NX-API enabled and ensure proper security configurations are maintained across all network infrastructure components.