CVE-2002-1101 in VPN 3000 Concentrator
Summary
by MITRE
Cisco VPN 3000 Concentrator 2.2.x, 3.6(Rel), and 3.x before 3.5.5, allows remote attackers to cause a denial of service via a long user name.
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Analysis
by VulDB Data Team • 09/09/2024
The Cisco VPN 3000 Concentrator vulnerability identified as CVE-2002-1101 represents a classic buffer overflow condition that affects multiple versions of Cisco's enterprise VPN infrastructure software. This vulnerability specifically targets the authentication processing mechanism within the concentrator software, where the system fails to properly validate the length of user name inputs during the authentication process. The flaw exists in versions 2.2.x, 3.6(Rel), and 3.x before 3.5.5, indicating a widespread issue that impacted a significant portion of Cisco's VPN concentrator deployments during that period. The vulnerability operates through a stack-based buffer overflow condition where an attacker can craft a maliciously long user name that exceeds the allocated buffer space, causing the application to crash and resulting in a denial of service condition for legitimate users attempting to establish VPN connections.
The technical exploitation of this vulnerability follows the ATT&CK framework's privilege escalation and denial of service tactics, specifically mapping to T1499.004 for network denial of service and T1068 for local privilege escalation through application vulnerabilities. The underlying cause aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. When a remote attacker submits an excessively long user name, the concentrator's authentication daemon processes this input without proper length validation, leading to memory corruption that ultimately results in system crash and service disruption. The vulnerability demonstrates poor input validation practices where the software assumes all user inputs will conform to expected parameters without implementing adequate bounds checking mechanisms.
The operational impact of CVE-2002-1101 extends beyond simple service disruption to potentially compromise the availability of critical enterprise communications infrastructure. Organizations relying on Cisco VPN 3000 Concentrators for remote access and site-to-site connections would experience immediate and significant business disruption when this vulnerability is exploited. The denial of service condition affects all users attempting to authenticate through the affected concentrator, creating cascading effects throughout the organization's remote access capabilities. Network administrators would face challenges in identifying and mitigating the attack since the symptoms manifest as complete service unavailability rather than more subtle behavioral anomalies. The vulnerability also exposes the broader risk of attackers using such denial of service conditions as precursors to more sophisticated attacks, as the service disruption can be used to mask other malicious activities or create opportunities for additional exploitation attempts.
Mitigation strategies for this vulnerability require immediate implementation of software updates and patches provided by Cisco to address the buffer overflow condition in the affected concentrator versions. Organizations should implement network segmentation and access controls to limit exposure of vulnerable concentrators to untrusted networks, while also deploying intrusion detection systems to monitor for suspicious authentication attempts that might indicate exploitation attempts. The remediation process should include thorough testing of patched software in controlled environments before deployment to production systems to ensure that the patch does not introduce compatibility issues with existing network configurations. Additionally, implementing rate limiting and authentication throttling mechanisms can help reduce the effectiveness of automated exploitation attempts while network administrators monitor for signs of attempted exploitation. The vulnerability highlights the critical importance of maintaining current security patches and implementing robust input validation controls across all network infrastructure components to prevent similar issues from affecting enterprise security posture.