End-of-life (EOL) industrial IoT devices create a growing cybersecurity challenge for operational technology (OT) environments. While these devices often remain functional, they pose significant and frequently overlooked security risks. When vendors no longer provide updates or support, critical infrastructure becomes vulnerable to emerging threats. Organizations need practical strategies to manage these risks without disrupting operations or compromising safety. Why EOL equipment creates vulnerabilities Using hardware and software without vendor support introduces vulnerabilities that attackers can actively exploit. Unlike traditional IT systems, OT security must account for unique performance, reliability and safety requirements that end-of-life devices cannot guarantee. These systems control physical processes where failures can lead to production shutdowns, equipment damage or worker injuries. The threat goes beyond theoretical concerns. The 2016 Mirai botnet attack weaponized IoT devices to disrupt major internet services and popular websites, demonstrating how attackers could turn consumer devices against critical infrastructure. Federal lawmakers responded by creating the IoT Cybersecurity Improvement Act of 2020, which establishes strict security standards for federal IoT deployments. The legislation acknowledges that unsecured devices pose serious risks to military operations, healthcare systems and other essential services. Strategies for securing end-of-life IoT devices Organizations often cannot immediately replace every end-of-life device in their environment. Budget constraints, operational requirements and supply chain limitations force extended use of outdated equipment. The recognized set of best practices from the CIS Controls provides a defense-in-depth framework for securing industrial control systems when standard patching isn’t feasible. For strengthened security on EOL devices, teams can do the following. 1. Conduct a full asset inventory Organizations cannot protect assets they don't know exist. A comprehensive inventory documents every OT device and IIoT sensor on the network, including make, model, firmware version and network location. This baseline enables security teams to identify which devices have reached end-of-life status and