CVE-2002-1092 in VPN 3000 Concentrator
Summary
by MITRE
Cisco VPN 3000 Concentrator 3.6(Rel) and earlier, and 2.x.x, when configured to use internal authentication with group accounts and without any user accounts, allows remote VPN clients to log in using PPTP or IPSEC user authentication.
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Analysis
by VulDB Data Team • 05/16/2019
The vulnerability identified as CVE-2002-1092 represents a critical authentication flaw in Cisco VPN 3000 Concentrator appliances running version 3.6(Rel) and earlier, as well as 2.x.x series software. This issue stems from improper access control implementation within the authentication subsystem, specifically affecting configurations that utilize internal authentication with group accounts while lacking individual user accounts. The flaw creates an unintended pathway for unauthorized network access that directly violates fundamental security principles of authentication and authorization.
The technical root cause of this vulnerability lies in the improper handling of authentication requests when the system is configured with group-based authentication but no individual user accounts exist. When remote VPN clients attempt to establish connections using either PPTP or IPSEC authentication protocols, the system fails to properly validate the authentication credentials against the intended user account database. This misconfiguration allows any client presenting valid group credentials to bypass normal authentication checks and gain network access. The vulnerability operates at the network layer and authentication protocol level, making it particularly dangerous as it can be exploited without requiring prior knowledge of specific user credentials.
The operational impact of CVE-2002-1092 is substantial and far-reaching for organizations relying on Cisco VPN 3000 concentrators for secure remote access. Attackers can leverage this vulnerability to establish unauthorized VPN connections and gain access to protected internal networks, potentially leading to data breaches, system compromise, and unauthorized access to sensitive information. The vulnerability affects both PPTP and IPSEC authentication methods, providing attackers with multiple exploitation vectors. Organizations with this vulnerability present in their network infrastructure face significant risk of unauthorized network penetration, especially when the affected devices are configured in environments with minimal user account management.
This vulnerability aligns with CWE-287, which addresses improper authentication issues in software systems, and maps to ATT&CK technique T1078.004 for valid accounts and T1566 for phishing attacks that could exploit this weakness. The flaw essentially creates a backdoor authentication mechanism that bypasses normal access controls, making it particularly dangerous in environments where network segmentation and access control are critical security measures. Organizations should consider implementing network monitoring to detect unusual authentication patterns that might indicate exploitation attempts.
Mitigation strategies for CVE-2002-1092 require immediate attention and include updating to Cisco VPN 3000 Concentrator software versions that address this authentication flaw, typically versions 3.6(2) or later. Organizations should also implement proper user account management practices, ensuring that authentication configurations include appropriate user account definitions rather than relying solely on group accounts. Network segmentation and access control policies should be reviewed and strengthened to limit the potential impact of any successful exploitation attempts. Additionally, implementing network monitoring solutions that can detect anomalous authentication behavior and conducting regular security audits of VPN configurations will help identify and remediate similar vulnerabilities before they can be exploited by malicious actors.