CVE-2001-0204 in Firebox II
Summary
by MITRE
Watchguard Firebox II allows remote attackers to cause a denial of service by establishing multiple connections and sending malformed PPTP packets.
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Analysis
by VulDB Data Team • 04/08/2019
The vulnerability identified as CVE-2001-0204 affects Watchguard Firebox II network security appliances, representing a significant denial of service weakness that can be exploited remotely by malicious actors. This issue specifically targets the appliance's handling of Point-to-Point Tunneling Protocol (PPTP) connections, which are commonly used for creating virtual private networks and remote access solutions. The vulnerability arises from insufficient input validation and connection management within the firewall's PPTP processing subsystem, creating a pathway for attackers to disrupt legitimate network services through carefully crafted network traffic.
The technical flaw manifests when an attacker establishes multiple concurrent connections to the Firebox II device and subsequently sends malformed PPTP packets designed to exploit weaknesses in the connection handling logic. These malformed packets trigger buffer overflows or memory corruption conditions within the device's PPTP processing modules, causing the system to become unstable and eventually crash or become unresponsive. The vulnerability is particularly concerning because it requires minimal privileges to exploit and can be executed from any remote location with network access to the affected appliance, making it a high-impact threat for organizations relying on Watchguard Firebox II for network security.
From an operational impact perspective, this vulnerability can severely disrupt business continuity by rendering the network security appliance completely inaccessible, effectively removing a critical defense mechanism from the network perimeter. Organizations may experience complete loss of network connectivity, unauthorized access to internal systems, and extended downtime while technicians investigate and remediate the issue. The attack can be executed with relatively simple tools and does not require sophisticated exploitation techniques, making it accessible to a broad range of threat actors including script kiddies and organized cybercriminals. The vulnerability affects the availability aspect of the CIA triad, directly compromising the network's ability to maintain consistent service delivery and access control.
The exploit demonstrates characteristics aligned with attack patterns documented in the MITRE ATT&CK framework under the T1498 technique for 'Network Denial of Service' and T1071.101 for 'Application Layer Protocol: Web Protocols' when considering the network protocol manipulation aspects. This vulnerability also maps to CWE-121, which describes 'Stack-based Buffer Overflow', and CWE-122, 'Heap-based Buffer Overflow', indicating the memory corruption mechanisms at play. Organizations should implement immediate mitigations including disabling PPTP services if not required, implementing connection rate limiting, and deploying network intrusion detection systems to monitor for suspicious connection patterns. Additionally, regular firmware updates from Watchguard and comprehensive network segmentation strategies should be implemented to reduce the attack surface and limit the potential impact of similar vulnerabilities. The incident underscores the critical importance of proper input validation and robust error handling in network security appliances, particularly when processing protocol-specific traffic that may contain maliciously crafted data.