CVE-2002-1093 in VPN 3000 Concentrator
Summary
by MITRE
HTML interface for Cisco VPN 3000 Concentrator 2.x.x and 3.x.x before 3.0.3(B) allows remote attackers to cause a denial of service (CPU consumption) via a long URL request.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 05/16/2019
The vulnerability identified as CVE-2002-1093 represents a critical denial of service weakness in Cisco VPN 3000 Concentrator appliances running software versions 2.x.x and 3.x.x prior to 3.0.3(B). This flaw resides within the HTML interface component of the VPN concentrator, which serves as the primary administrative and user access point for configuring and managing the device. The vulnerability specifically targets the URL parsing mechanism that processes incoming web requests through the device's HTTP interface, creating a condition where malformed or excessively long URL parameters can trigger abnormal CPU utilization patterns.
The technical implementation of this vulnerability stems from inadequate input validation within the web server component of the Cisco VPN 3000 Concentrator. When a remote attacker crafts a specially formatted HTTP request containing an unusually long URL parameter, the device's parsing routine fails to properly handle the excessive input length, leading to a condition where the CPU becomes consumed in an infinite loop or excessive processing cycles. This occurs because the device's internal URL parsing algorithm does not implement proper bounds checking or input length limitations, allowing maliciously crafted requests to cause the system to continuously process the malformed URL until system resources are exhausted.
The operational impact of CVE-2002-1093 extends beyond simple service disruption, as it can effectively render the entire VPN concentrator appliance unusable to legitimate users and administrators. Once exploited, the vulnerability causes sustained high CPU utilization that can persist until the device is manually restarted or the system reboots. This creates a significant risk for organizations relying on these concentrators for remote access and network connectivity, as the denial of service can occur without any authentication requirements, making it particularly dangerous for attackers who may not have legitimate access credentials. The vulnerability also affects the device's ability to process legitimate VPN connections, potentially causing cascading failures in remote access services that organizations depend upon for business continuity.
This vulnerability aligns with CWE-121, which addresses buffer overflow conditions, and more specifically with CWE-770, which covers excessive resource consumption. The attack pattern follows the methodology described in the MITRE ATT&CK framework under T1499.004, which covers network denial of service attacks. Organizations should implement immediate mitigations including applying the vendor-supplied patch version 3.0.3(B) or higher, implementing network-level rate limiting for HTTP requests to the VPN concentrator's web interface, and configuring firewall rules to restrict access to the administrative interface from trusted networks only. Additionally, monitoring for unusual CPU utilization patterns and implementing intrusion detection systems can help identify exploitation attempts before they cause significant service disruption. The vulnerability highlights the critical importance of input validation and resource management in network infrastructure devices, particularly those serving as primary access points for enterprise networks.