CVE-1999-1204 is a high-severity vulnerability affecting Check Point Firewall-1, an early and widely used firewall product. The vulnerability arises from improper handling of certain restricted keywords such as "Mail", "auth", and "time" within user-defined objects. When these keywords are used in firewall rules, the system may incorrectly generate a rule with a default "ANY" address. This misconfiguration can unintentionally broaden access permissions, allowing traffic to reach more systems than intended by the firewall administrator. The vulnerability impacts the confidentiality, integrity, and availability of network resources by potentially exposing sensitive systems to unauthorized access or malicious traffic. The CVSS score of 7.5 reflects the network-based attack vector, low attack complexity, no authentication requirement, and partial to complete compromise of confidentiality, integrity, and availability. Although this vulnerability was published in 1998 and no patches are available, it remains relevant in legacy environments where Firewall-1 is still in use. No known exploits are reported in the wild, but the nature of the flaw means that attackers could exploit misconfigured rules to bypass intended access controls.

For European organizations, this vulnerability could lead to unauthorized access to critical internal systems, data leakage, and potential disruption of services. Organizations relying on Check Point Firewall-1, especially legacy systems in sectors such as finance, government, and critical infrastructure, may face increased risk of lateral movement by attackers or exposure of sensitive data. The inadvertent expansion of access due to misinterpreted keywords could undermine network segmentation and perimeter defenses, increasing the attack surface. Given the high severity and the fact that no patch is available, organizations must carefully audit firewall configurations to prevent accidental exposure. The impact is amplified in environments where Firewall-1 is integrated into complex network architectures or where compensating controls are weak or absent.

Since no patch is available for this vulnerability, European organizations should implement the following practical mitigations: 1) Conduct a thorough audit of all user-defined objects and firewall rules in Check Point Firewall-1 to identify any use of restricted keywords such as "Mail", "auth", and "time". 2) Replace or rename these keywords in firewall configurations to avoid triggering the default "ANY" address behavior. 3) Implement strict change management and review processes for firewall rule modifications to catch misconfigurations early. 4) Employ network segmentation and additional access controls to limit the impact of any unintended access. 5) Where feasible, plan and execute migration from legacy Firewall-1 systems to modern, supported firewall solutions with active security updates. 6) Monitor network traffic for unusual access patterns that could indicate exploitation attempts. 7) Use compensating controls such as intrusion detection/prevention systems (IDS/IPS) to detect and block unauthorized traffic that might exploit this vulnerability.