CVE-2019-1808 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 patch on an affected device. The vulnerability is due to improper verification of digital signatures for patch images. An attacker could exploit this vulnerability by loading an unsigned software patch on an affected device. A successful exploit could allow the attacker to boot a malicious software patch image.
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Analysis
by VulDB Data Team • 09/21/2023
The vulnerability identified as CVE-2019-1808 resides within the Image Signature Verification mechanism of Cisco NX-OS Software, representing a critical security flaw that undermines the integrity protection of network infrastructure devices. This weakness specifically targets the digital signature validation process that should ensure only authorized and verified software updates can be installed on Cisco network switches and routers running NX-OS. The vulnerability operates at the system level where patch verification procedures fail to properly validate the authenticity of software images, creating an exploitable condition that can be leveraged by malicious actors with administrative privileges.
The technical flaw manifests when the NX-OS software fails to adequately verify digital signatures associated with patch images during the installation process. This improper verification allows an attacker to bypass the normal security controls that should prevent unauthorized software modifications. The vulnerability stems from a weakness in the cryptographic validation routines that should confirm the patch image originates from a legitimate source and has not been tampered with during transit or storage. Attackers can exploit this by preparing a malicious software patch with a forged signature that appears valid to the system's verification routines, effectively circumventing the intended security controls.
From an operational perspective, this vulnerability creates a severe risk for network infrastructure security as it allows authenticated attackers with administrator-level privileges to compromise the integrity of network devices. The successful exploitation enables an attacker to install malicious software patches that could persistently compromise the device's functionality, potentially leading to complete system takeover or the installation of backdoors. The impact extends beyond individual device compromise to potentially affect entire network segments, as compromised network devices can serve as entry points for broader network infiltration. This vulnerability directly impacts the CIA triad, specifically undermining the integrity and availability of network infrastructure by allowing unauthorized modifications to critical system components.
Organizations affected by this vulnerability should implement immediate mitigations including restricting administrative access to network devices, implementing strict patch management procedures with proper signature verification, and monitoring for unauthorized software installations. The vulnerability aligns with CWE-330 use of insecure entropy sources and CWE-311 missing encryption of sensitive data, while also mapping to ATT&CK techniques such as T1068 legitimate credential use and T1014 rootkit installation. Network security teams should deploy additional monitoring controls to detect anomalous patch installation activities and ensure that all software updates are obtained from official Cisco channels with proper digital signatures verified through trusted processes. The recommended approach includes disabling unnecessary patch installation capabilities, implementing multi-factor authentication for administrative access, and conducting regular security audits of installed software components to detect any unauthorized modifications.