CVE-2019-1690 in Application Policy Infrastructure Controller
Summary
by MITRE
A vulnerability in the management interface of Cisco Application Policy Infrastructure Controller (APIC) software could allow an unauthenticated, adjacent attacker to gain unauthorized access on an affected device. The vulnerability is due to a lack of proper access control mechanisms for IPv6 link-local connectivity imposed on the management interface of an affected device. An attacker on the same physical network could exploit this vulnerability by attempting to connect to the IPv6 link-local address on the affected device. A successful exploit could allow the attacker to bypass default access control restrictions on an affected device. Cisco Application Policy Infrastructure Controller (APIC) devices running versions prior to 4.2(0.21c) are affected.
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Analysis
by VulDB Data Team • 07/31/2023
The vulnerability identified as CVE-2019-1690 represents a critical access control flaw within Cisco's Application Policy Infrastructure Controller software ecosystem. This issue specifically targets the management interface of APIC devices, which serve as central controllers for managing network policies and security configurations in data center environments. The flaw stems from inadequate access control mechanisms that fail to properly restrict IPv6 link-local connectivity on the management interface, creating an exploitable pathway for unauthorized access. The vulnerability affects Cisco APIC devices running software versions prior to 4.2(0.21c), making a significant portion of deployed infrastructure potentially susceptible to exploitation. This represents a fundamental failure in network device security architecture where the management plane lacks proper isolation and authentication controls, particularly concerning IPv6 addressing mechanisms that are commonly used in modern network environments.
The technical exploitation of this vulnerability relies on the attacker's physical proximity to the target device within the same network segment. IPv6 link-local addresses are automatically configured for network interfaces and are designed for local communication only, but in this case, the APIC software fails to properly enforce access restrictions on these addresses. An attacker positioned on the same physical network can attempt to establish connections to the IPv6 link-local address of the management interface, potentially bypassing default access control restrictions that should normally prevent unauthorized management access. This type of attack falls under the category of adjacent network attacks where physical network proximity is required, but the attack vector demonstrates how insufficient network segmentation and access control enforcement can create significant security weaknesses in enterprise infrastructure. The vulnerability is classified under CWE-284, which specifically addresses improper access control mechanisms, and aligns with ATT&CK technique T1071.004 for application layer protocol usage in network communications.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it provides attackers with potential entry points into critical network infrastructure management systems. APIC devices control network policies and security configurations across large enterprise networks, making successful exploitation particularly dangerous. An attacker who gains access through this vulnerability could potentially modify network policies, disable security controls, or establish persistent access points within the network infrastructure. The implications are severe given that APIC devices are typically deployed in mission-critical environments where they manage core network security policies and application delivery controllers. The vulnerability essentially creates a backdoor into the management plane that could be leveraged for more sophisticated attacks, including privilege escalation, data exfiltration, or network reconnaissance. Organizations with deployed APIC devices running vulnerable software versions face significant risk of compromise, particularly in environments where physical network security controls are insufficient or where network segmentation is not properly enforced.
Mitigation strategies for this vulnerability should focus on immediate software upgrades to versions 4.2(0.21c) or later, which contain the necessary access control fixes. Network administrators should also implement additional security measures including network segmentation to isolate management interfaces from general network traffic, implementing proper firewall rules to restrict access to management interfaces, and ensuring that IPv6 link-local addressing is properly controlled on network devices. The vulnerability highlights the importance of proper network device configuration and access control enforcement, particularly for management interfaces that are critical to network security operations. Organizations should conduct comprehensive vulnerability assessments to identify all affected devices and implement layered security controls beyond simple software patching. The incident underscores the need for robust security practices in managing network infrastructure devices, including regular security assessments, proper network segmentation, and maintaining current software versions to protect against known vulnerabilities. This vulnerability also reinforces the importance of implementing defense-in-depth strategies where multiple security controls work together to protect critical infrastructure components from various attack vectors.