CVE-2016-6466 in ASR 5000
Summary
by MITRE
A vulnerability in the IPsec component of StarOS for Cisco ASR 5000 Series routers could allow an unauthenticated, remote attacker to terminate all active IPsec VPN tunnels and prevent new tunnels from establishing, resulting in a denial of service (DoS) condition. This vulnerability affects the following Cisco products: Cisco ASR 5000/5500 Series routers, Cisco Virtualized Packet Core (VPC). More Information: CSCva13631. Known Affected Releases: 20.0.0 20.1.0 20.2.0 20.2.3 20.2.v1 21.0.0 21.0.M0.64246. Known Fixed Releases: 20.2.3 20.2.3.65026 20.2.a4.65307 20.2.v1 20.2.v1.65353 20.3.M0.65037 20.3.T0.65043 21.0.0 21.0.0.65256 21.0.M0.64595 21.0.M0.64860 21.0.M0.65140 21.0.V0.65052 21.0.V0.65150 21.0.V0.65366 21.0.VC0.64639 21.1.A0.64861 21.1.A0.65145 21.1.PP0.65270 21.1.R0.65130 21.1.R0.65135 21.1.R0.65154 21.1.VC0.64898 21.1.VC0.65203 21.2.A0.65147.
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Analysis
by VulDB Data Team • 10/04/2022
The vulnerability identified as CVE-2016-6466 represents a critical denial of service weakness within the IPsec implementation of Cisco's StarOS operating system, specifically affecting the ASR 5000 Series routers and related infrastructure. This flaw resides in the secure communication protocols that establish and maintain IPsec virtual private network connections, creating an avenue for remote exploitation without requiring authentication credentials. The vulnerability's impact extends beyond individual devices to potentially disrupt enterprise-wide secure communication networks that depend on these routers as core infrastructure components. The affected products include not only the primary ASR 5000/5500 Series hardware but also the Cisco Virtualized Packet Core platform, indicating the widespread nature of the potential compromise across different network domains.
Technical analysis reveals that the flaw manifests in the IPsec processing logic where the system fails to properly validate incoming packets or handle specific sequence of operations during tunnel establishment and maintenance phases. This allows an unauthenticated remote attacker to craft malicious traffic that triggers a state machine failure within the IPsec subsystem, causing the complete termination of existing secure tunnels while simultaneously blocking the creation of new ones. The vulnerability operates at the network protocol level, specifically targeting the IPsec key exchange and authentication mechanisms that are fundamental to maintaining secure communications across enterprise networks. This represents a classic example of a protocol-level vulnerability that can be exploited through carefully constructed network traffic without requiring sophisticated attack infrastructure or insider knowledge of the target environment.
The operational impact of CVE-2016-6466 is severe and potentially catastrophic for organizations relying on IPsec VPN connectivity for remote access, branch office connections, and secure data transmission. When exploited, the vulnerability creates an immediate and complete disruption of secure network communications, forcing network administrators to implement emergency procedures to restore connectivity and potentially affecting business continuity operations. The attack vector is particularly dangerous because it requires no authentication credentials, making it accessible to any remote attacker with basic network connectivity and minimal technical expertise. Organizations with extensive IPsec deployments across multiple locations could experience widespread service degradation or complete network outages, particularly in environments where redundant secure connections are critical for operational resilience. The vulnerability's presence in multiple software versions indicates that it was a persistent issue requiring multiple patches across different release streams.
Mitigation strategies for this vulnerability involve immediate deployment of Cisco's security advisories and software updates that address the specific IPsec processing flaw. Network administrators should prioritize patching affected systems, particularly those running the known vulnerable releases including versions 20.0.0 through 21.0.M0.64246, with particular attention to the fixed releases that contain the necessary code modifications to prevent the exploitation. The remediation process should include comprehensive testing of patched systems to ensure that legitimate IPsec functionality remains intact while the vulnerability is addressed. Organizations should also implement network monitoring solutions to detect anomalous traffic patterns that might indicate exploitation attempts, and consider temporary network segmentation to limit the potential impact should the vulnerability be exploited in production environments. This vulnerability aligns with CWE-119 which addresses weak input validation in network protocols, and represents a significant concern within the ATT&CK framework under the privilege escalation and denial of service categories, emphasizing the need for robust network security controls and continuous monitoring of critical infrastructure components.