CVE-2004-2120 in Web Server
Summary
by MITRE
Reptile Web Server allows remote attackers to cause a denial of service (CPU consumption) via multiple incomplete GET requests without the HTTP version.
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Analysis
by VulDB Data Team • 01/12/2025
The CVE-2004-2120 vulnerability affects the Reptile Web Server, a lightweight HTTP server implementation that was widely used in embedded systems and network appliances during the early 2000s. This vulnerability represents a classic example of a resource exhaustion attack that exploits the server's inadequate handling of malformed HTTP requests. The flaw specifically manifests when the server receives multiple GET requests that lack the HTTP version specification, creating a condition where the server consumes excessive CPU resources while attempting to process these incomplete requests. This type of vulnerability falls under the category of denial of service attacks and aligns with CWE-400, which addresses improper handling of exceptional conditions that can lead to resource exhaustion. The Reptile Web Server's implementation fails to properly validate incoming HTTP request formats, particularly the absence of the required HTTP version string that should be present in all valid HTTP/1.1 requests according to RFC 2616 standards.
The technical exploitation of this vulnerability occurs through a carefully crafted sequence of incomplete HTTP GET requests that omit the HTTP version component such as HTTP/1.1. When the Reptile Web Server receives these malformed requests, it enters an infinite loop or excessive processing state while attempting to parse and handle the incomplete data. The server's protocol handling code lacks proper validation mechanisms to detect and reject malformed requests before initiating resource-intensive processing operations. This behavior creates a situation where an attacker can continuously send such incomplete requests, causing the server to consume 100% CPU utilization and effectively rendering the web service unavailable to legitimate users. The vulnerability demonstrates a fundamental flaw in input validation and protocol compliance, where the server fails to implement proper request parsing and error handling routines that would normally be expected in robust HTTP implementations. This issue represents a clear violation of the principle of least privilege and proper error handling as defined in security best practices.
The operational impact of CVE-2004-2120 extends beyond simple service disruption to potentially compromise entire network infrastructure when the affected Reptile Web Server is deployed in critical applications such as network appliances, embedded systems, or industrial control systems. The CPU consumption attack can be particularly devastating in resource-constrained environments where the server may not have sufficient processing power to handle legitimate traffic while under attack. Network administrators may find their systems becoming unresponsive and requiring manual intervention to restore service, which can be especially problematic in environments where automated monitoring and response systems are not properly configured. This vulnerability also exposes the broader risk of inadequate protocol implementation in embedded systems, where security considerations are often secondary to functionality and performance requirements. The attack vector is particularly effective because it requires minimal sophistication from the attacker and can be executed using simple network tools, making it a popular choice for denial of service attacks against vulnerable systems. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network denial of service, and the T1595.001 technique for reconnaissance through network scanning to identify vulnerable systems.
Mitigation strategies for CVE-2004-2120 should focus on implementing proper input validation and request parsing mechanisms within the Reptile Web Server implementation. The most effective approach involves updating the server software to properly validate HTTP request formats and reject malformed requests before processing begins. Network-level mitigations include implementing rate limiting and connection throttling mechanisms to prevent a single client from overwhelming the server with incomplete requests. Firewalls and intrusion prevention systems can be configured to detect and block HTTP requests lacking proper version specifications, particularly when these requests arrive in high volumes. System administrators should also consider implementing monitoring solutions that can detect unusual CPU usage patterns and automatically trigger alerts when the server begins consuming excessive resources. The vulnerability highlights the importance of following established security guidelines and standards such as those outlined in the OWASP Top Ten and NIST Cybersecurity Framework, which emphasize the need for proper input validation and resource management in web applications. Additionally, organizations should conduct regular security assessments to identify and remediate similar vulnerabilities in their network infrastructure, particularly in legacy systems that may not receive regular security updates. The long-term solution requires upgrading to more modern web server implementations that have robust security features and proper handling of malformed requests, as the Reptile Web Server itself is no longer maintained or supported.