CVE-2003-0785 in ipmasq
Summary
by MITRE
ipmasq before 3.5.12, in certain configurations, may forward packets to the external interface even if the packets are not associated with an established connection, which could allow remote attackers to bypass intended filtering.
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Analysis
by VulDB Data Team • 06/29/2021
The vulnerability identified as CVE-2003-0785 affects ipmasq versions prior to 3.5.12 and represents a significant flaw in network address translation and packet filtering mechanisms. This issue resides within the ipmasq component which is part of the Linux kernel's netfilter framework, specifically impacting how the system handles packet forwarding decisions. The vulnerability stems from improper state tracking and connection validation within the masquerading functionality, creating a scenario where packets can be forwarded without proper verification of their connection state. This represents a classic case of insufficient access control and improper state management that directly impacts network security policies.
The technical flaw manifests when ipmasq operates in certain configurations where it fails to properly validate whether incoming packets belong to established connections before forwarding them to external interfaces. This misconfiguration allows packets to traverse the network boundary even when they should be blocked by firewall rules or connection tracking mechanisms. The vulnerability specifically impacts the connection tracking subsystem where the kernel's netfilter framework should maintain state information about active connections but fails to enforce proper validation checks. This flaw directly violates the principle of least privilege and proper network segmentation, as packets that should be filtered based on connection state are permitted to proceed through the network stack.
From an operational impact perspective, this vulnerability enables remote attackers to bypass intended network filtering and access control measures that are designed to prevent unauthorized communication between internal and external networks. The attack vector allows adversaries to exploit the misconfigured packet forwarding behavior to establish unauthorized communication channels or to access services that should be restricted to internal network users only. This vulnerability can potentially enable various attack scenarios including port scanning, service enumeration, and unauthorized access to internal network resources. The impact is particularly severe in environments where ipmasq is used for network address translation and firewall protection, as it undermines the fundamental security model of the network infrastructure.
Mitigation strategies for CVE-2003-0785 primarily involve upgrading to ipmasq version 3.5.12 or later where the connection tracking and packet forwarding logic has been corrected. Network administrators should also implement additional security measures such as proper firewall rule configuration, connection tracking enforcement, and regular security audits of network infrastructure components. The vulnerability aligns with CWE-284 Access Control Issues and can be mapped to ATT&CK techniques involving network penetration and privilege escalation through network infrastructure manipulation. Organizations should also consider implementing network segmentation strategies and monitoring for anomalous packet forwarding behavior to detect potential exploitation attempts. This vulnerability demonstrates the critical importance of proper state management in network security components and the potential for configuration flaws to create significant security weaknesses in fundamental network infrastructure elements.