CVE-2018-3948 in TL-R600VPN
Summary
by MITRE
An exploitable denial-of-service vulnerability exists in the URI-parsing functionality of the TP-Link TL-R600VPN HTTP server. A specially crafted URL can cause the server to stop responding to requests, resulting in downtime for the management portal. An attacker can send either an unauthenticated or authenticated web request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 06/12/2023
The CVE-2018-3948 vulnerability represents a critical denial-of-service weakness in TP-Link TL-R600VPN devices that specifically targets the HTTP server's URI-parsing capabilities. This flaw resides within the web interface implementation of the router's management portal, where the system fails to properly handle malformed or specially crafted URLs during the parsing process. The vulnerability affects the device's ability to maintain responsive service delivery, potentially causing complete service interruption for network administrators who rely on the web management interface for device configuration and monitoring.
The technical exploitation mechanism involves sending malformed HTTP requests containing specially crafted URI sequences that trigger buffer overflow conditions or infinite loop scenarios within the HTTP server's parsing logic. When the server attempts to process these malformed URLs, the parsing routine becomes trapped in an unresponsive state, causing the entire HTTP service to become unavailable. This behavior manifests as the management portal ceasing to respond to any incoming requests, effectively rendering the device inaccessible through its web interface until manual intervention or device reboot occurs. The vulnerability demonstrates characteristics consistent with CWE-121 stack-based buffer overflow conditions where insufficient input validation leads to memory corruption.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network management capabilities and availability. Network administrators who depend on the web interface for routine device maintenance, configuration changes, and monitoring activities face significant operational risks when this vulnerability is exploited. The unauthenticated nature of the attack means that any external party can trigger the denial-of-service condition without requiring prior access credentials, making the vulnerability particularly dangerous in publicly accessible network environments. This weakness directly impacts the availability component of the CIA triad and can be classified under ATT&CK technique T1499.004 for network denial of service attacks.
Mitigation strategies for CVE-2018-3948 should prioritize immediate firmware updates from TP-Link to address the underlying parsing logic flaws. Network administrators should implement network segmentation to isolate critical devices and limit exposure to potential attackers. Additional protective measures include deploying web application firewalls to filter malformed HTTP requests and implementing monitoring solutions to detect unusual traffic patterns that may indicate exploitation attempts. The vulnerability highlights the importance of proper input validation and bounds checking in web server implementations, aligning with security best practices outlined in OWASP Top Ten and NIST guidelines for secure coding practices. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other network infrastructure components that may present similar attack vectors.