CVE-2013-1124 in Network Admission Control
Summary
by MITRE
The Cisco Network Admission Control (NAC) agent on Mac OS X does not verify the X.509 certificate of an Identity Services Engine (ISE) server during an SSL session, which allows man-in-the-middle attackers to spoof ISE servers via an arbitrary certificate, aka Bug ID CSCub24309.
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Analysis
by VulDB Data Team • 04/26/2017
The vulnerability identified as CVE-2013-1124 represents a critical security flaw in Cisco Network Admission Control (NAC) agent implementations on Mac OS X systems. This weakness specifically targets the certificate verification process during SSL sessions between the NAC agent and Cisco Identity Services Engine (ISE) servers, creating a significant attack vector for malicious actors seeking to compromise network access controls. The vulnerability stems from the absence of proper X.509 certificate validation mechanisms within the Mac OS X NAC agent implementation, which fails to authenticate the legitimacy of the ISE server's SSL certificate during the connection establishment phase.
The technical flaw manifests as a failure in the SSL/TLS certificate validation process, where the NAC agent on Mac OS X systems accepts any valid X.509 certificate presented by an attacker without performing the necessary verification steps. This omission creates a man-in-the-middle attack scenario where an adversary can position themselves between the NAC agent and the legitimate ISE server, presenting a fraudulent certificate that appears valid to the client system. The vulnerability directly relates to CWE-295, which addresses improper certificate validation in secure communications, and represents a fundamental breakdown in the trust establishment process that should normally be enforced by proper SSL/TLS implementation. The attack requires minimal sophistication as the attacker only needs to intercept network traffic and present a certificate signed by a trusted authority, making this vulnerability particularly dangerous in enterprise environments where network access control is critical.
The operational impact of this vulnerability extends beyond simple certificate validation failure, as it fundamentally undermines the security posture of Cisco NAC implementations on Mac OS X systems. Network administrators who rely on NAC for access control and device authentication face significant risks, as attackers can bypass authentication mechanisms and gain unauthorized network access. The vulnerability affects the integrity of the entire network admission control process, potentially allowing malicious actors to impersonate legitimate ISE servers and grant access to unauthorized devices or users. This compromise directly relates to ATT&CK technique T1550.003, which covers use of valid credentials for unauthorized access, and can enable further attacks by providing a foothold within the network infrastructure. Organizations using Cisco NAC for security enforcement may experience complete loss of access control capabilities, as the system can no longer reliably distinguish between legitimate and malicious ISE servers.
Mitigation strategies for this vulnerability require immediate implementation of multiple defensive measures to protect against exploitation. Organizations should prioritize updating their Cisco NAC agent implementations to versions that properly enforce X.509 certificate validation, while also implementing network-level controls such as certificate pinning or additional SSL inspection mechanisms. The remediation process involves ensuring that all Mac OS X systems running Cisco NAC agents receive appropriate security updates from Cisco, which should include proper certificate validation routines. Network administrators should also consider implementing additional monitoring for unusual SSL connection patterns or certificate-related events that might indicate an active attack. The vulnerability demonstrates the critical importance of proper certificate validation in secure communications and highlights the need for organizations to maintain updated security implementations across all network components. Security controls should include regular vulnerability assessments to identify similar certificate validation issues in other network security tools, and organizations should establish processes for rapid deployment of security patches to prevent exploitation of such fundamental authentication flaws.