CVE-2007-4414 in VPN Client
Summary
by MITRE
Cisco VPN Client on Windows before 4.8.02.0010 allows local users to gain privileges by enabling the "Start Before Logon" (SBL) and Microsoft Dial-Up Networking options, and then interacting with the dial-up networking dialog box.
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Analysis
by VulDB Data Team • 07/24/2019
The vulnerability identified as CVE-2007-4414 affects Cisco VPN Client versions prior to 4.8.02.0010 on Windows operating systems, representing a significant privilege escalation flaw that leverages specific client configuration settings to enable unauthorized system access. This vulnerability operates through a combination of client-side configuration parameters that create an exploitable condition when combined with user interaction. The flaw specifically targets the Windows environment where the Cisco VPN client is configured with the "Start Before Logon" feature and Microsoft Dial-Up Networking enabled, creating a dangerous intersection of system services that can be manipulated by local attackers.
The technical mechanism behind this vulnerability stems from how the Cisco VPN client handles authentication and authorization processes when the SBL feature is enabled. When both the Start Before Logon option and Microsoft Dial-Up Networking are active, the client creates a window of opportunity where the dial-up networking dialog box can be manipulated to execute code with elevated privileges. This occurs because the client does not properly validate the security context of user interactions with the dial-up dialog, allowing malicious input to bypass normal authentication checks. The vulnerability manifests when an attacker interacts with the dial-up networking interface, potentially triggering a code execution path that elevates privileges from standard user to administrative level.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it represents a critical weakness in the Windows authentication model that could enable attackers to establish persistent access to systems. Local users who can manipulate the Cisco VPN client configuration can exploit this flaw to gain administrative privileges without requiring legitimate credentials, effectively undermining the security boundaries of the Windows environment. This vulnerability is particularly concerning because it operates at the system level rather than requiring network access, making it exploitable even in isolated network segments. The attack vector is relatively simple as it only requires local access and the ability to modify client configuration settings, making it accessible to attackers with basic system privileges.
Security practitioners should note that this vulnerability aligns with CWE-284, which addresses improper access control, and demonstrates how client-side configuration issues can create significant security weaknesses. The flaw also relates to ATT&CK technique T1068, which covers local privilege escalation through the exploitation of system configuration vulnerabilities. Mitigation strategies must include immediate patching of Cisco VPN client to version 4.8.02.0010 or later, along with configuration reviews to disable unnecessary features like Start Before Logon when they are not required for business operations. Network administrators should also implement strict access controls and monitor for unauthorized changes to VPN client configurations. Additionally, the principle of least privilege should be enforced by ensuring that users only have the minimum required permissions to perform their duties, reducing the potential impact if this vulnerability is exploited. The vulnerability highlights the importance of proper security configuration management and the need for regular security assessments of client software components that interact with system-level services.