CVE-2017-6767 in Application Policy Infrastructure Controller
Summary
by MITRE
A vulnerability in Cisco Application Policy Infrastructure Controller (APIC) could allow an authenticated, remote attacker to gain higher privileges than the account is assigned. The attacker will be granted the privileges of the last user to log in, regardless of whether those privileges are higher or lower than what should have been granted. The attacker cannot gain root-level privileges. The vulnerability is due to a limitation with how Role-Based Access Control (RBAC) grants privileges to remotely authenticated users when login occurs via SSH directly to the local management interface of the APIC. An attacker could exploit this vulnerability by authenticating to the targeted device. The attacker's privilege level will be modified to match that of the last user to log in via SSH. An exploit could allow the attacker to gain elevated privileges and perform CLI commands that should be restricted by the attacker's configured role. Cisco Bug IDs: CSCvc34335. Known Affected Releases: 1.0(1e), 1.0(1h), 1.0(1k), 1.0(1n), 1.0(2j), 1.0(2m), 1.0(3f), 1.0(3i), 1.0(3k), 1.0(3n), 1.0(4h), 1.0(4o); 1.1(0.920a), 1.1(1j), 1.1(3f); 1.2 Base, 1.2(2), 1.2(3), 1.2.2; 1.3(1), 1.3(2), 1.3(2f); 2.0 Base, 2.0(1).
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/09/2021
The vulnerability identified as CVE-2017-6767 resides within Cisco's Application Policy Infrastructure Controller (APIC) system, representing a critical flaw in the platform's Role-Based Access Control (RBAC) implementation. This security weakness specifically affects the authentication and privilege assignment mechanisms when users connect via SSH to the local management interface of the APIC device. The flaw creates a dangerous privilege escalation scenario where an authenticated attacker can manipulate their effective privilege level to match that of the most recently logged-in user, regardless of the original assigned permissions. This behavior fundamentally undermines the security model designed to maintain least-privilege access principles and creates a significant risk for network administrators who rely on the APIC for critical infrastructure management.
The technical nature of this vulnerability stems from a design limitation in how the APIC handles RBAC assignments for remotely authenticated users connecting through SSH. When a user establishes an SSH session to the APIC management interface, the system fails to properly validate and maintain the privilege boundaries established by the user's configured role. Instead, the system dynamically assigns the connecting user's privileges based on the last authenticated session's privilege level, creating a race condition where privilege levels are not properly isolated between concurrent users. This issue is particularly concerning because it operates at the authentication layer, affecting the core security controls that should prevent unauthorized access to restricted administrative functions. The vulnerability specifically impacts the APIC's privilege management system and represents a clear violation of the principle of least privilege, which is a fundamental security concept that aligns with CWE-284 access control weaknesses.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary Command Line Interface (CLI) commands that should normally be restricted based on their assigned role. An attacker who successfully exploits this vulnerability could potentially perform administrative actions that exceed their legitimate permissions, including modifying network policies, accessing sensitive configuration data, or executing operations that could compromise the entire network infrastructure managed by the APIC. This risk is particularly severe in enterprise environments where the APIC serves as a central controller for network policies and security configurations, as unauthorized privilege elevation could lead to widespread network disruption or data compromise. The vulnerability affects multiple release versions of the APIC software, indicating a widespread issue that required patching across various software generations. The fact that the attacker cannot gain root-level privileges suggests the vulnerability operates within a constrained privilege model but still provides substantial access that could be leveraged for significant damage.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. Cisco has released patches addressing CSCvc34335, which should be deployed immediately across all affected APIC installations to resolve the privilege escalation issue. Organizations should implement strict network segmentation to limit direct SSH access to APIC management interfaces, reducing the attack surface for this specific vulnerability. Additionally, security teams should establish monitoring protocols to detect unusual privilege changes or unauthorized access patterns that might indicate exploitation attempts. The vulnerability's presence in multiple software releases underscores the importance of maintaining up-to-date security patches and implementing comprehensive vulnerability management processes. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and credential access methods, highlighting the need for robust access control monitoring and user behavior analytics to detect anomalous authentication patterns that could indicate exploitation attempts. Organizations should also consider implementing multi-factor authentication and additional access controls to provide defense-in-depth against similar privilege escalation scenarios.