CVE-2019-1590 in NX-OS
Summary
by MITRE
A vulnerability in the Transport Layer Security (TLS) certificate validation functionality of Cisco Nexus 9000 Series Application Centric Infrastructure (ACI) Mode Switch Software could allow an unauthenticated, remote attacker to perform insecure TLS client authentication on an affected device. The vulnerability is due to insufficient TLS client certificate validations for certificates sent between the various components of an ACI fabric. An attacker who has possession of a certificate that is trusted by the Cisco Manufacturing CA and the corresponding private key could exploit this vulnerability by presenting a valid certificate while attempting to connect to the targeted device. An exploit could allow the attacker to gain full control of all other components within the ACI fabric of an affected device.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2019-1590 resides within the Transport Layer Security certificate validation mechanisms of Cisco Nexus 9000 Series switches operating in Application Centric Infrastructure mode. This represents a critical flaw in the security architecture of enterprise networking infrastructure, where the proper validation of TLS client certificates fails to adequately verify the authenticity and integrity of connecting components. The vulnerability specifically impacts the inter-component communication within Cisco ACI fabrics, where multiple devices must authenticate with each other to maintain network integrity and prevent unauthorized access to sensitive network operations.
The technical root cause of this vulnerability stems from insufficient validation checks during the TLS client certificate authentication process. When components within an ACI fabric attempt to establish secure connections, the system fails to properly validate that the presented certificates originate from legitimate sources within the trusted certificate authority chain. This weakness allows an attacker to exploit the system by obtaining a certificate from the Cisco Manufacturing CA and its corresponding private key, effectively bypassing the normal authentication procedures. The flaw essentially permits certificate impersonation attacks where malicious actors can present valid certificates to gain unauthorized access to network components.
The operational impact of this vulnerability extends far beyond simple network disruption, as it enables complete compromise of the affected ACI fabric. An attacker who successfully exploits this vulnerability can gain full control over all other components within the fabric, effectively becoming a privileged user with extensive network access rights. This represents a severe privilege escalation scenario where a remote unauthenticated attacker can assume control of critical network infrastructure, potentially leading to data breaches, network disruption, and unauthorized access to sensitive corporate information. The implications are particularly concerning given that ACI fabrics typically manage core enterprise networking functions and may contain sensitive operational data.
This vulnerability aligns with CWE-295, which addresses "Improper Certificate Validation," and maps to ATT&CK technique T1078 for Valid Accounts and T1566 for Phishing, as the exploitation requires possession of valid credentials and certificate materials. The attack vector represents a man-in-the-middle scenario where network components are tricked into accepting fraudulent certificates, allowing for lateral movement within the fabric and potential full network compromise. Organizations should implement immediate mitigations including certificate revocation for affected systems, enhanced monitoring of certificate usage patterns, and verification of certificate trust chains. Additionally, network segmentation and additional authentication layers should be considered to limit the potential blast radius of such an attack, as the vulnerability affects the fundamental trust mechanisms of the network infrastructure.