CVE-2004-2472 in Outpost Firewall
Summary
by MITRE
Agnitum Outpost Pro Firewall 2.1 allows remote attackers to cause a denial of service (CPU consumption) via a flood of small, invalid packets, which can not be processed quickly enough by Outpost Pro.
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Analysis
by VulDB Data Team • 10/08/2018
The vulnerability identified as CVE-2004-2472 represents a significant denial of service weakness in Agnitum Outpost Pro Firewall version 2.1 that operates at the network layer of the OSI model. This flaw exploits the firewall's insufficient packet processing capabilities when confronted with maliciously crafted network traffic, specifically targeting the device's ability to handle invalid packet fragments. The vulnerability demonstrates a classic resource exhaustion attack pattern where an attacker can overwhelm the system's processing capabilities through a high volume of malformed packets that require additional computational resources to analyze and discard. The attack vector leverages the firewall's insufficient input validation mechanisms, which fail to properly filter or quickly reject invalid network packets before they consume excessive CPU cycles.
The technical implementation of this vulnerability occurs when the Outpost Pro Firewall receives a flood of small, invalid packets that do not conform to standard network protocols or firewall processing expectations. These packets are typically designed to trigger specific processing paths within the firewall's network stack that involve complex validation routines or error handling mechanisms. The flaw stems from inadequate buffer management and packet parsing algorithms that cannot efficiently handle the volume of invalid packets without consuming disproportionate CPU resources. This creates a scenario where legitimate network traffic becomes degraded or blocked as the firewall's CPU utilization spikes to unsustainable levels, effectively rendering the security device ineffective for its intended purpose.
The operational impact of this vulnerability extends beyond simple service disruption to encompass complete system compromise and potential security breaches. When the firewall becomes overwhelmed with CPU consumption, it cannot properly inspect legitimate network traffic for potential threats, creating a false sense of security for network administrators. The vulnerability specifically targets the firewall's packet processing engine, which is critical for maintaining network security boundaries and enforcing access controls. This creates a dangerous situation where the very device designed to protect the network becomes a point of failure that can be exploited by attackers to gain unauthorized access to protected systems. The attack can be executed remotely without requiring authentication, making it particularly dangerous for perimeter security devices. According to CWE classification, this vulnerability maps to CWE-400, which covers resource exhaustion conditions, and aligns with ATT&CK technique T1498, which addresses resource exhaustion attacks.
Mitigation strategies for this vulnerability require both immediate and long-term approaches to address the underlying design flaw in the firewall's packet processing architecture. Organizations should implement network segmentation to isolate critical systems from the affected firewall, deploy rate limiting mechanisms to control packet flow, and establish monitoring systems to detect abnormal CPU utilization patterns. The most effective immediate solution involves upgrading to a newer version of the firewall software that includes improved packet validation and processing optimizations. Additionally, implementing network intrusion detection systems can help identify and block malicious packet floods before they overwhelm the firewall. Network administrators should also configure the firewall to drop invalid packets at the earliest possible point in the processing pipeline and establish baseline CPU utilization thresholds that trigger automated alerts or system shutdowns to prevent complete service disruption. The vulnerability highlights the importance of proper input validation and resource management in security appliances, as outlined in security standards that emphasize robust error handling and denial of service protection mechanisms.