CVE-2017-12333 in NX-OS
Summary
by MITRE
A vulnerability in Cisco NX-OS System Software could allow an authenticated, local attacker to bypass signature verification when loading a software image. The vulnerability is due to insufficient NX-OS signature verification for software images. An authenticated, local attacker could exploit this vulnerability to bypass signature verification and load a crafted, unsigned software image on a targeted device. The attacker would need valid administrator credentials to perform this exploit. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Unified Computing System Manager. Cisco Bug IDs: CSCvf25045, CSCvf31495.
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Analysis
by VulDB Data Team • 01/25/2021
The vulnerability identified as CVE-2017-12333 represents a critical security flaw in Cisco NX-OS System Software that undermines the integrity verification mechanisms designed to protect network infrastructure devices. This weakness specifically affects the signature verification process that is fundamental to ensuring only authorized and verified software components are installed on Cisco networking equipment. The vulnerability exists within the software image loading mechanism where insufficient validation procedures fail to properly authenticate the digital signatures associated with software updates and patches. Attackers exploiting this flaw can manipulate the system's trust model by bypassing the standard verification protocols that are meant to prevent unauthorized code execution on critical network infrastructure. The security implications are particularly severe because this vulnerability requires only local access with administrative privileges, making it accessible to insiders or attackers who have already gained administrative access to the system. The affected products include enterprise-grade switches and unified computing systems that form the backbone of many network infrastructures, potentially exposing organizations to significant operational risks. This vulnerability directly relates to CWE-315 which addresses the exposure of sensitive information in the context of authentication and authorization mechanisms, and it aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1547.001 which covers 'Registry Run Keys / Startup Folder' in the context of persistence mechanisms that could be leveraged through unauthorized software installation.
The technical exploitation of CVE-2017-12333 requires an authenticated attacker with administrator-level credentials to manipulate the software loading process on affected Cisco devices. The flaw manifests when the system attempts to verify software signatures, where the NX-OS software fails to properly validate the cryptographic signatures associated with software images. This allows an attacker to craft and install unsigned software images that would normally be rejected by the system's security controls. The vulnerability essentially creates a backdoor within the legitimate software installation process, enabling attackers to deploy malicious code or unauthorized modifications without triggering the system's built-in security warnings. The impact extends beyond simple code execution as it compromises the entire software integrity chain that is essential for maintaining network security. When exploited, this vulnerability can lead to complete system compromise and potentially enable attackers to establish persistent access to network infrastructure. The affected Cisco products operate in mission-critical environments where such vulnerabilities can have cascading effects on network availability and security posture.
Organizations running the affected Cisco NX-OS systems face significant operational risks when this vulnerability remains unaddressed, as it provides a pathway for attackers to bypass fundamental security controls that protect against malicious software installation. The vulnerability affects multiple product lines including the Multilayer Director Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, and Unified Computing System Manager, indicating a widespread exposure across Cisco's enterprise networking portfolio. The security implications extend beyond immediate code execution capabilities to include potential privilege escalation and persistent access mechanisms that could be leveraged for extended network infiltration. This vulnerability represents a serious threat to network integrity because it allows attackers to install modified software versions that could include backdoors, monitoring tools, or other malicious components. The attack vector is particularly concerning because it requires only local administrative access, suggesting that either insider threats or compromised administrative accounts could exploit this weakness. Organizations should consider this vulnerability in the context of broader security frameworks including the NIST Cybersecurity Framework and ISO 27001 standards for information security management, where such flaws could represent critical gaps in system integrity controls.
The recommended mitigations for CVE-2017-12333 involve immediate deployment of Cisco's official security patches and updates that address the signature verification weakness in NX-OS software. Organizations should prioritize patching affected systems to ensure that the proper signature validation mechanisms are restored and functioning correctly. Network administrators should implement additional monitoring procedures to detect unauthorized software installations or modifications to system components. The vulnerability highlights the importance of maintaining strict access controls and implementing principle of least privilege for administrative accounts to limit the potential impact of compromised credentials. Security teams should also consider implementing network segmentation and additional logging controls to detect anomalous software installation activities. Organizations should conduct thorough vulnerability assessments to identify all affected devices and ensure complete remediation across their entire network infrastructure. The mitigation strategy should include regular security audits of software installation processes and verification of digital signatures for all system updates. Additionally, organizations should review their incident response procedures to ensure readiness for potential exploitation of this vulnerability, as the ability to bypass signature verification represents a significant threat to network security integrity and could enable attackers to establish persistent access to critical network infrastructure components.