CVE-2000-0779 in Firewall-1
Summary
by MITRE
Checkpoint Firewall-1 with the RSH/REXEC setting enabled allows remote attackers to bypass access restrictions and connect to a RSH/REXEC client via malformed connection requests.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability identified as CVE-2000-0779 represents a critical security flaw in Checkpoint Firewall-1 systems that specifically affects the Remote Shell (RSH) and Remote Execution (REXEC) protocols when these services are enabled on the firewall. This issue stems from improper handling of malformed connection requests that allows unauthorized remote attackers to establish connections to RSH/REXEC clients through the firewall, effectively bypassing the intended access controls and network segmentation policies that the firewall is designed to enforce.
The technical flaw manifests in the firewall's protocol handling mechanism where it fails to properly validate incoming connection requests destined for RSH/REXEC services. When these services are enabled, the firewall should act as a secure gateway that controls access to these inherently insecure protocols, but due to the vulnerability, malformed connection attempts can slip through the validation checks and establish unauthorized connections to internal RSH/REXEC clients. This represents a classic case of insufficient input validation and protocol parsing error that directly violates the principle of least privilege and secure network boundary enforcement.
The operational impact of this vulnerability is severe and multifaceted, as it fundamentally undermines the security posture of organizations relying on Checkpoint Firewall-1 for network protection. Attackers can exploit this weakness to gain unauthorized access to systems that would normally be protected by the firewall's RSH/REXEC filtering rules, potentially leading to full system compromise, data exfiltration, and lateral movement within the network. The vulnerability is particularly dangerous because RSH and REXEC protocols are known for their weak security models, relying on simple password authentication without encryption, making them prime targets for exploitation when improperly filtered through network security devices.
This vulnerability maps directly to CWE-20, which describes "Improper Input Validation" and aligns with ATT&CK technique T1071.004 for application layer protocol usage, specifically targeting remote services. The flaw also relates to CWE-540, which addresses the inclusion of sensitive information in error messages, as the malformed connection handling could potentially expose system information to attackers. Organizations using Checkpoint Firewall-1 with RSH/REXEC services enabled face significant risk of compromise, as the vulnerability allows attackers to circumvent the firewall's intended security functions and access internal services that should remain protected.
Mitigation strategies for this vulnerability should include immediate disabling of RSH/REXEC services on the firewall when not absolutely necessary, as these protocols are fundamentally insecure and should be replaced with more secure alternatives such as SSH. Network administrators should also implement additional monitoring and logging of connection attempts to RSH/REXEC ports to detect potential exploitation attempts. The firewall should be updated to the latest available patches from Checkpoint, and organizations should conduct thorough network audits to identify and remove any unnecessary RSH/REXEC services. Additionally, implementing network segmentation and access control lists that further restrict access to RSH/REXEC ports can provide additional layers of protection against exploitation attempts.