CVE-2004-1473 in Enterprise Firewall
Summary
by MITRE
Symantec Enterprise Firewall/VPN Appliances 100, 200, and 200R running firmware before 1.63 and Gateway Security 320, 360, and 360R running firmware before 622 allow remote attackers to bypass filtering and determine whether the device is running services such as tftpd, snmpd, or isakmp via a UDP port scan with a source port of UDP 53.
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Analysis
by VulDB Data Team • 11/21/2024
This vulnerability affects Symantec Enterprise Firewall and VPN appliances including models 100, 200, 200R, and Gateway Security 320, 360, and 360R devices. The flaw resides in the packet filtering mechanism of these network security appliances, specifically in how they handle UDP port scanning attempts. The vulnerability stems from improper validation of incoming packets and inadequate response handling when receiving UDP packets with source port 53, which is typically associated with DNS queries. This weakness allows attackers to perform reconnaissance and bypass the device's filtering capabilities through a sophisticated port scanning technique.
The technical implementation of this vulnerability involves sending UDP packets with source port 53 to the affected devices. When these packets are processed, the appliance fails to properly validate the packet structure and source information, leading to inconsistent behavior in its filtering rules. Attackers can exploit this by crafting specific UDP packets that trigger different responses from the device depending on whether certain services like tftpd, snmpd, or isakmp are running. This differential response enables the attacker to map out the device's service configuration and identify running services without proper authentication or authorization. The vulnerability is particularly concerning because it operates at the network layer where the device should be enforcing strict filtering policies.
The operational impact of this vulnerability extends beyond simple reconnaissance as it provides attackers with critical information about the target network infrastructure. By determining which services are active on the appliance, attackers can tailor subsequent attacks to exploit known vulnerabilities in those specific services. This information gathering capability represents a significant threat to network security posture, as it allows adversaries to bypass the appliance's intended protection mechanisms. The vulnerability essentially undermines the fundamental security model of the device by providing a method for remote attackers to gain knowledge about the internal state and service configuration without requiring authentication. This aligns with attack patterns described in the MITRE ATT&CK framework under reconnaissance techniques, specifically targeting network service discovery and enumeration.
The root cause of this vulnerability can be classified as a weakness in input validation and response handling, which corresponds to CWE-20, "Improper Input Validation," and CWE-254, "Security Features Weakness." The flaw demonstrates poor implementation of network packet processing where the device fails to properly validate source port information and maintain consistent filtering behavior regardless of packet characteristics. Organizations running these affected devices face significant risk as the vulnerability allows for information disclosure and service enumeration that could lead to more sophisticated attacks. The impact is particularly severe because these appliances are typically deployed as core security components in enterprise networks, making them attractive targets for attackers seeking to compromise network perimeters.
Mitigation strategies should focus on immediate firmware updates to versions 1.63 or higher for Enterprise Firewall/VPN appliances and firmware 622 or higher for Gateway Security devices. Network administrators should also implement additional monitoring and logging of unusual UDP traffic patterns, particularly those originating from source port 53. Network segmentation and additional access controls should be implemented to limit the potential impact of successful exploitation. Security teams should conduct comprehensive network audits to identify all affected devices and ensure proper patch management processes are in place. The vulnerability highlights the importance of robust input validation in network security appliances and demonstrates the critical need for thorough testing of packet handling mechanisms before deployment in production environments.