CVE-2000-0150 in Firewall-1
Summary
by MITRE
Check Point Firewall-1 allows remote attackers to bypass port access restrictions on an FTP server by forcing it to send malicious packets that Firewall-1 misinterprets as a valid 227 response to a client's PASV attempt.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability described in CVE-2000-0150 represents a critical security flaw in Check Point Firewall-1 that exploits a weakness in how the firewall handles FTP protocol responses. This vulnerability specifically targets the passive mode (PASV) implementation within FTP connections, creating a pathway for remote attackers to circumvent port access controls that are typically enforced by the firewall. The flaw demonstrates a classic example of protocol interpretation error where legitimate network behavior is misinterpreted as malicious activity, leading to unauthorized access. The vulnerability operates at the application layer of the network stack, specifically affecting the FTP protocol handling capabilities of the firewall system.
The technical mechanism behind this vulnerability involves the manipulation of FTP control channel communications to force the firewall into misinterpreting network packets. When an FTP client attempts to establish a data connection in passive mode, the server responds with a 227 response containing IP address and port information for the data connection. The Check Point Firewall-1 incorrectly processes specially crafted packets that mimic this 227 response format, causing the firewall to believe that the connection originates from an allowed source rather than the actual attacker. This misinterpretation effectively bypasses the firewall's access control policies and allows unauthorized access to FTP server resources. The vulnerability stems from inadequate validation of FTP response formats and insufficient state tracking of FTP protocol sessions within the firewall's processing logic.
The operational impact of this vulnerability extends beyond simple access bypass, as it fundamentally compromises the integrity of the firewall's network access controls. Attackers can leverage this weakness to gain unauthorized access to FTP servers protected by the Check Point Firewall-1, potentially leading to data breaches, system compromise, and unauthorized file transfers. The vulnerability affects the firewall's ability to properly enforce network security policies, creating a backdoor that can be exploited by remote attackers without requiring authentication or direct system access. This represents a significant threat to organizations relying on the firewall for network protection, as it undermines the core security function of controlling access to network resources. The impact is particularly severe in environments where FTP services are commonly used for file transfers and where the firewall is expected to provide comprehensive access control.
Organizations affected by this vulnerability should implement immediate mitigations including updating to patched versions of Check Point Firewall-1, implementing additional network segmentation controls, and monitoring for suspicious FTP activity patterns. The vulnerability aligns with CWE-254, which addresses security weaknesses in protocol implementation, and demonstrates characteristics similar to ATT&CK technique T1071.004 for application layer protocol usage. Network administrators should also consider implementing additional intrusion detection systems to monitor for anomalous FTP responses and establish more robust logging mechanisms to track FTP protocol interactions. The recommended approach includes both immediate patch deployment and long-term architectural improvements to prevent similar protocol interpretation flaws from compromising network security controls.