CVE-2019-1812 in NX-OS
Summary
by MITRE
A vulnerability in the Image Signature Verification feature of Cisco NX-OS Software could allow an authenticated, local attacker with administrator-level credentials to install a malicious software image on an affected device. The vulnerability exists because software digital signatures are not properly verified during CLI command execution. An attacker could exploit this vulnerability to install an unsigned software image on an affected device.
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Analysis
by VulDB Data Team • 09/21/2023
The vulnerability identified as CVE-2019-1812 resides within the Image Signature Verification functionality of Cisco NX-OS Software, representing a critical security flaw that undermines the integrity protection mechanisms of network infrastructure devices. This weakness specifically targets the authentication and verification processes that should prevent unauthorized software modifications on Cisco networking equipment, creating a pathway for malicious actors to compromise device firmware integrity.
The technical root cause of this vulnerability stems from improper verification of digital signatures during command execution within the command line interface. When administrators execute software installation commands, the system should validate that the digital signatures match the expected cryptographic fingerprints of legitimate software packages. However, the flaw allows the system to accept unsigned software images without proper verification, effectively bypassing the security controls designed to prevent unauthorized modifications. This failure in signature validation creates a direct attack vector where malicious code can be installed without detection, as the system fails to enforce the cryptographic integrity checks that are fundamental to software authenticity verification.
The operational impact of this vulnerability is severe and multifaceted, as it enables authenticated local attackers with administrator-level privileges to perform unauthorized software installations on affected Cisco NX-OS devices. This compromise can lead to complete system takeover, persistent backdoor installation, and potential network-wide disruption. Attackers can exploit this vulnerability to deploy malware, modify network configurations, or establish persistent access points within the network infrastructure. The vulnerability essentially undermines the principle of least privilege and integrity protection that network devices should maintain, allowing privilege escalation and unauthorized modification of critical system components.
From a cybersecurity perspective, this vulnerability aligns with CWE-311, which addresses the absence of proper cryptographic verification mechanisms, and represents a significant deviation from the security principles outlined in the NIST Cybersecurity Framework. The attack pattern follows the MITRE ATT&CK framework's technique T1068, which involves the use of legitimate credentials to gain access and execute malicious code. Organizations utilizing Cisco NX-OS software face heightened risk of supply chain attacks, where attackers can leverage this vulnerability to install malicious firmware that persists across system reboots and remains undetected by standard monitoring mechanisms.
The recommended mitigations for this vulnerability include immediate implementation of Cisco's security advisories and software patches that restore proper signature verification mechanisms. Network administrators should enforce strict access controls and privilege management, limiting administrator credentials to only those who require them for legitimate operations. Additional protective measures include implementing network segmentation, monitoring for unauthorized software installations, and conducting regular security audits of network device configurations. Organizations should also consider implementing endpoint detection and response solutions that can monitor for suspicious installation activities and unauthorized modifications to system images, as the vulnerability creates a persistent threat vector that can be exploited for long-term network compromise.