CVE-2002-0604 in Lite+ Firewall
Summary
by MITRE
Snapgear Lite+ firewall 1.5.3 and 1.5.4 allows remote attackers to cause a denial of service (crash) via a large number of packets with malformed IP options.
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Analysis
by VulDB Data Team • 04/12/2019
The vulnerability described in CVE-2002-0604 affects Snapgear Lite+ firewall versions 1.5.3 and 1.5.4, representing a significant security flaw that enables remote attackers to execute denial of service attacks against affected systems. This issue stems from insufficient input validation mechanisms within the firewall's packet processing pipeline, specifically when handling IP packets containing malformed options. The vulnerability operates at the network layer, targeting the fundamental packet parsing capabilities of the firewall software. According to the CWE (Common Weakness Enumeration) framework, this corresponds to CWE-129, which describes improper validation of length parameters, and CWE-128, which addresses the handling of malformed input data. The attack vector leverages the firewall's failure to properly sanitize incoming IP packets with malformed options, creating a condition where the system becomes vulnerable to resource exhaustion or unexpected behavior leading to system instability.
The technical implementation of this vulnerability involves the firewall's inability to handle malformed IP options gracefully during packet processing. When the firewall receives packets containing excessive or malformed IP options, the parsing routine fails to properly validate the option length fields or handle unexpected data structures. This leads to buffer overflows, memory corruption, or other internal state inconsistencies that cause the system to crash or become unresponsive. The attack requires only a sufficient volume of specially crafted packets to trigger the vulnerability, making it particularly dangerous in network environments where the firewall serves as a critical infrastructure component. The vulnerability demonstrates poor error handling practices and inadequate defensive programming techniques, as the system does not implement proper bounds checking or input sanitization mechanisms. From an ATT&CK perspective, this vulnerability maps to T1498, which covers network denial of service, and T1071.004, covering application layer protocol traffic, since the attack targets the application layer processing of network packets.
The operational impact of this vulnerability extends beyond simple system crashes, potentially causing significant disruption to network services and business operations. Organizations relying on Snapgear Lite+ firewalls for network security may experience complete service outages during attack execution, as the firewall becomes unavailable to process legitimate network traffic. The vulnerability's remote nature means that attackers can exploit it from outside the network perimeter without requiring local access or authentication credentials, making it particularly dangerous for perimeter defense systems. Network administrators may face challenges in detecting and mitigating such attacks, as the symptoms manifest as complete service disruption rather than more subtle indicators of compromise. The vulnerability also represents a potential escalation path for attackers who may use it as a stepping stone for further network infiltration, as the firewall's crash state could create opportunities for additional exploitation attempts. Organizations should consider implementing network segmentation and redundant security controls to minimize the impact of such vulnerabilities, while also ensuring that all firewall firmware is kept up to date with security patches.
The remediation approach for this vulnerability requires immediate patching of affected Snapgear Lite+ firewall versions to address the underlying packet parsing logic. System administrators should prioritize updating to versions that include proper input validation and bounds checking mechanisms for IP options processing. Additionally, network administrators should implement rate limiting and packet filtering rules to reduce the impact of potential attacks, while also establishing monitoring procedures to detect unusual packet patterns that may indicate exploitation attempts. The vulnerability highlights the importance of defensive programming practices and proper input validation in network security appliances, emphasizing the need for comprehensive testing of edge cases in packet processing routines. Organizations should also consider implementing intrusion detection systems that can identify and alert on malformed packet patterns, providing early warning capabilities for potential exploitation attempts. Regular vulnerability assessments and security audits of network infrastructure components remain essential for identifying similar weaknesses in other security appliances and network devices that may be similarly vulnerable to malformed input processing attacks.