The Node.js runtime is a JavaScript execution environment that runs outside the browser. It combines the V8 engine with system APIs for files, networking, processes, and other operating-system tasks, allowing JavaScript to behave like a full application platform. Developers use it to build servers, automation tools, update agents, and command-line utilities.
In cyber security, Node.js matters because the same features that make it useful also make it attractive to attackers. Malware can bundle a Node.js runtime to execute scripts on a victim machine without needing a browser, and defenders may see JavaScript logic hidden inside packaged or compiled artifacts rather than readable source code. That can slow triage and require runtime analysis, version-matched tooling, and host-based monitoring. On the defense side, Node.js logs, process behavior, outbound connections, and unexpected script execution are useful signals for spotting suspicious activity.