When the Gateway Has No Password: A Security Audit of the TP-Link TL-WR841ND Running LEDE 17.01.7

This paper presents a white-box security audit of the TP-Link TL-WR841ND (v8.2) consumer router running LEDE 17.01.7 (r4030-6028f00df0), a widely deployed legacy firmware environment based on OpenWrt. Through systematic configuration analysis conducted in a controlled laboratory setting, ten architectural vulnerabilities are identified spanning authentication failures (CWE-258, CWE-306, CWE-521), network protocol weaknesses (CWE-290, CWE-319), and firmware integrity deficiencies (CWE-347). Each finding is mapped to its CVSS 3.1 base score and MITRE ATT&CK technique. A STRIDE threat model and a four-layer mitigation framework are presented. Findings demonstrate that legacy SOHO routers with absent enforced credentials and lacking cryptographic firmware verification present a systemic risk to all devices sharing the same local network, particularly in open wireless configurations.