CVE-2005-4197 in SSL VPN
Summary
by MITRE
tunnelform.yaws in Nortel SSL VPN 4.2.1.6 allows remote attackers to execute arbitrary commands via a link in the a parameter, which is executed with extra privileges in a cryptographically signed Java Applet.
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Analysis
by VulDB Data Team • 11/22/2024
The vulnerability identified as CVE-2005-4197 resides within the tunnelform.yaws component of Nortel SSL VPN version 4.2.1.6, representing a critical remote code execution flaw that exploits a command injection vulnerability through improper input validation. This weakness specifically manifests when the application processes a link parameter within the a parameter of the tunnelform.yaws component, creating a pathway for malicious actors to inject and execute arbitrary commands on the affected system with elevated privileges. The vulnerability is particularly concerning because it operates within a cryptographically signed Java Applet environment, which inherently grants the executed code additional system access rights beyond normal application boundaries.
The technical exploitation of this vulnerability stems from insufficient sanitization of user-supplied input within the parameter handling mechanism of the SSL VPN client interface. When a specially crafted link containing malicious command sequences is passed through the a parameter, the system fails to properly validate or escape the input before processing it within the context of the signed Java Applet. This allows attackers to leverage the applet's cryptographic signature to execute arbitrary code with the privileges of the underlying system, effectively bypassing traditional security boundaries. The flaw constitutes a classic command injection vulnerability that operates at the application layer, where user input directly influences system command execution without proper authorization checks or input filtering mechanisms.
The operational impact of this vulnerability extends beyond simple remote code execution, as it enables attackers to gain full system compromise of the affected Nortel SSL VPN appliance. The privilege escalation aspect of this vulnerability means that successful exploitation can result in complete system takeover, data exfiltration, and potential lateral movement within the network. Security professionals should note that this vulnerability affects an SSL VPN implementation, making it particularly dangerous in enterprise environments where such appliances serve as primary network access points for remote users. The cryptographic signing of the Java Applet component amplifies the risk, as it removes the typical sandboxing restrictions that would normally prevent such privilege escalation attacks. This vulnerability aligns with CWE-77 and CWE-94 categories, representing command injection and code injection weaknesses respectively, while also mapping to ATT&CK technique T1059.007 for command and scripting interpreter usage in remote access scenarios.
Mitigation strategies for CVE-2005-4197 should focus on immediate patch application from Nortel, as the vendor would have released a security update addressing the input validation flaw. Organizations should implement network segmentation to limit access to the affected SSL VPN infrastructure and deploy network monitoring solutions to detect suspicious parameter usage patterns. Additionally, security teams should consider disabling unnecessary Java applet functionality within the VPN client interface and implementing strict input validation policies for all user-supplied parameters. The vulnerability highlights the importance of proper privilege separation and input sanitization in cryptographic contexts, particularly when dealing with signed applets that operate with elevated system permissions. Organizations should also review their SSL VPN configurations to ensure that only necessary services are exposed and that proper access controls are implemented to minimize the attack surface. Given the age of this vulnerability, organizations should prioritize upgrading to modern SSL VPN solutions that incorporate more robust security measures and proper input validation frameworks to prevent similar issues from occurring in contemporary deployments.