CVE-2000-0895 in SOHO Firewall
Summary
by MITRE
Buffer overflow in HTTP server on the WatchGuard SOHO firewall allows remote attackers to cause a denial of service and possibly execute arbitrary code via a long GET request.
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Analysis
by VulDB Data Team • 05/09/2019
The vulnerability identified as CVE-2000-0895 represents a critical buffer overflow flaw within the HTTP server component of WatchGuard SOHO firewall appliances. This issue resides in the handling of incoming GET requests and demonstrates how poorly validated input can lead to severe system compromise. The vulnerability specifically affects the firewall's web-based management interface, which serves as the primary means for administrators to configure and monitor the device. When a remote attacker submits a GET request containing excessive data, the HTTP server fails to properly validate the input length, resulting in memory corruption that can trigger unpredictable behavior. The buffer overflow occurs in the parsing logic responsible for processing HTTP headers and request parameters, where insufficient bounds checking allows malicious input to overwrite adjacent memory regions. This flaw operates at the application layer and leverages the inherent trust placed in the web interface by both legitimate administrators and potential attackers. The vulnerability's exploitation potential extends beyond simple denial of service, as the memory corruption can be manipulated to execute arbitrary code with the privileges of the web server process, potentially compromising the entire firewall appliance.
The technical implementation of this vulnerability aligns with common buffer overflow patterns documented in CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw demonstrates characteristics of CWE-787, indicating an out-of-bounds write condition that occurs when a program writes data past the end of a buffer allocated in memory. From an operational perspective, this vulnerability provides attackers with a pathway to achieve persistent access to the network perimeter, as the WatchGuard SOHO firewall serves as a critical security gateway. The attack surface is particularly concerning because it targets the management interface, which is typically accessible from external networks and often requires minimal authentication for basic operations. The HTTP server component of the firewall has no effective input sanitization mechanisms in place, making it susceptible to malformed requests that can cause memory corruption. This vulnerability also aligns with ATT&CK technique T1210, which describes exploitation of weaknesses in remote services to gain system access, and T1499, which covers network denial of service attacks that can be executed through protocol manipulation.
The operational impact of CVE-2000-0895 extends significantly beyond simple service disruption, as successful exploitation can result in complete compromise of the firewall appliance. Remote attackers can leverage this vulnerability to execute arbitrary code with the privileges of the web server process, potentially gaining access to network traffic monitoring capabilities and administrative controls. The denial of service aspect of this vulnerability means that legitimate users cannot access the firewall management interface, effectively disabling the security appliance's functionality. In enterprise environments, this could lead to complete loss of network security monitoring, creating blind spots that attackers can exploit to move laterally within the network. The vulnerability's exploitation requires minimal technical skill, as attackers only need to craft a specially formatted GET request with excessive data. The attack can be executed from any location with network connectivity to the firewall's HTTP management port, making it particularly dangerous for remote management scenarios. Organizations relying on WatchGuard SOHO firewalls for network security are especially vulnerable, as these appliances often serve as the first line of defense against external threats. The vulnerability's persistence is enhanced by the fact that it affects the HTTP server component, which typically runs with elevated privileges and has access to core system resources, potentially allowing attackers to escalate privileges beyond the initial web server compromise. Network administrators who depend on the firewall's management interface for configuration changes face significant risk, as the compromise can occur without any visible indication of attack activity.
Mitigation strategies for CVE-2000-0895 require immediate action to address the root cause of the buffer overflow vulnerability. Organizations should implement network segmentation to isolate firewall management interfaces from external networks, reducing the attack surface for this particular vulnerability. The most effective immediate solution involves applying vendor-provided security patches or firmware updates that correct the input validation logic in the HTTP server component. Network administrators should also consider disabling the web management interface entirely when it is not actively required, as this eliminates the attack vector altogether. Implementing network access control lists to restrict access to the firewall's HTTP management port to trusted IP addresses can provide additional defense-in-depth. Regular security assessments should include testing for similar buffer overflow vulnerabilities in other network appliances and services. Monitoring network traffic for unusually long GET requests or malformed HTTP headers can help detect exploitation attempts before they succeed. The vulnerability also highlights the importance of implementing proper input validation and bounds checking in all network services, particularly those handling user-provided data. Organizations should establish incident response procedures that include immediate isolation of affected systems and comprehensive forensic analysis when such vulnerabilities are detected. Regular vulnerability scanning and penetration testing should be conducted to identify similar issues in other network infrastructure components, ensuring that the organization maintains a robust security posture against similar threats. The remediation process should also include reviewing and updating network security policies to prevent similar issues from occurring in newly deployed or updated systems.