CVE-2006-4981 in Sygate NAC
Summary
by MITRE
Symantec Sygate NAC allows physically proximate attackers to bypass control methods and join a local network by selecting a forged MAC address associated with an exception rule that (1) permits all non-Windows devices or (2) whitelists certain sets of Organizationally Unique Identifiers (OUIs).
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/23/2017
This vulnerability resides in Symantec Sygate Network Access Control (NAC) systems which are designed to enforce network security policies by controlling device access based on authentication and authorization mechanisms. The flaw represents a significant bypass issue that undermines the core security principle of network segmentation and access control. Attackers exploiting this vulnerability can manipulate their network interface to present a forged MAC address that matches an existing exception rule within the system configuration. This allows unauthorized devices to gain network access without proper authentication or authorization, effectively rendering the NAC controls ineffective.
The technical implementation of this vulnerability stems from insufficient validation of MAC address authenticity within the NAC enforcement mechanisms. When a device attempts to connect to the network, the system checks the presented MAC address against its configured rules and exception policies. The vulnerability occurs because the system accepts any MAC address that matches an existing exception rule without verifying that the address genuinely belongs to a legitimate device. This weakness enables attackers to craft MAC addresses that align with either broad exception rules permitting all non-Windows devices or specific whitelisted OUIs that represent certain organizations or device types.
From an operational impact perspective, this vulnerability creates a serious security risk for organizations relying on Sygate NAC for network access control. An attacker positioned physically near the target network can simply change their device's MAC address to match an existing exception rule and gain immediate network access without any authentication requirements. This bypass allows for potential lateral movement within the network, data exfiltration, and other malicious activities that would normally be prevented by proper access controls. The vulnerability essentially provides a backdoor that can be exploited by anyone with physical access to network infrastructure or the ability to manipulate network traffic at the data link layer.
The security implications extend beyond simple access bypass, as this vulnerability directly violates fundamental security principles outlined in the OWASP Top Ten and NIST cybersecurity frameworks. It represents a failure in the principle of least privilege and demonstrates a critical weakness in network authentication mechanisms. The vulnerability aligns with CWE-284 (Improper Access Control) and CWE-310 (Cryptographic Issues) categories, as it enables unauthorized access through flawed access control validation and potentially weak cryptographic implementations in the MAC address validation process. Organizations using this NAC solution face increased risk of insider threats, unauthorized device connections, and potential network compromise that could lead to broader security incidents.
Mitigation strategies should focus on implementing stronger MAC address validation mechanisms that verify the authenticity of network connections beyond simple address matching. Network administrators should review and tighten exception rules to minimize broad permissions such as "all non-Windows devices" and instead implement more granular controls with specific device identification requirements. Additional measures include implementing MAC address binding to specific network ports, deploying network access control systems that enforce multi-factor authentication, and ensuring that exception rules are reviewed regularly for unnecessary broad permissions. Organizations should also consider network segmentation strategies that limit the impact of compromised devices and implement continuous monitoring to detect unauthorized MAC address changes or suspicious network access patterns that may indicate exploitation attempts.