CVE-2005-2912 in WRT54G
Summary
by MITRE
Linksys WRT54G router allows remote attackers to cause a denial of service (CPU consumption and server hang) via an HTTP POST request with a negative Content-Length value.
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Analysis
by VulDB Data Team • 07/10/2019
The CVE-2005-2912 vulnerability affects the Linksys WRT54G wireless router, representing a classic denial of service flaw that exploits improper input validation in the HTTP server implementation. This vulnerability demonstrates how seemingly minor protocol handling issues can lead to significant operational disruptions in network infrastructure devices. The flaw specifically resides in the router's web management interface where it fails to properly validate the Content-Length header in HTTP POST requests, creating an opportunity for remote attackers to manipulate the device's resource consumption patterns.
The technical exploitation mechanism involves sending an HTTP POST request with a negative Content-Length value, which causes the router's HTTP server to process this malformed input in a way that consumes excessive CPU resources. This improper handling occurs at the application layer where the router's embedded web server attempts to interpret and process the malformed header without adequate bounds checking or input sanitization. The negative value triggers an infinite loop or excessive resource allocation within the processing logic, leading to sustained high CPU utilization that can cause the device to become unresponsive or completely hang.
From an operational impact perspective, this vulnerability represents a serious threat to network availability and business continuity. When exploited successfully, the denial of service condition can render the router inaccessible to legitimate users while maintaining the device's physical connectivity to the network. Network administrators may experience complete loss of management access to the device, forcing them to perform manual hardware resets or potentially requiring physical intervention to restore service. The vulnerability affects the router's ability to perform its core functions including routing, firewall operations, and wireless access management, creating cascading effects throughout the network infrastructure that depends on the device.
The vulnerability aligns with CWE-129, Input Validation, and CWE-20, Improper Input Validation, as it demonstrates how insufficient validation of HTTP headers can lead to resource exhaustion. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, Endpoint Denial of Service, and T1595.001, Network Denial of Service, representing both endpoint and network-level attack vectors. The attack surface is particularly concerning given that the vulnerability is remotely exploitable without authentication requirements, making it accessible to any attacker with network access to the device. This characteristic places the vulnerability in the category of critical network infrastructure threats that can be leveraged for both disruption and potential reconnaissance purposes.
Mitigation strategies should include firmware updates from Linksys or third-party vendors that implement proper input validation for HTTP headers and Content-Length values. Network administrators should consider implementing network segmentation to limit exposure of critical infrastructure devices to untrusted networks. Additional protective measures include configuring access control lists to restrict HTTP management access to trusted IP addresses only, deploying intrusion detection systems to monitor for suspicious HTTP traffic patterns, and implementing regular security assessments to identify similar vulnerabilities in other network equipment. The vulnerability underscores the importance of secure coding practices in embedded systems and the need for thorough input validation in all network services to prevent resource exhaustion attacks that can compromise availability and operational integrity.