An Extension ID is the unique identifier used to distinguish one extension from another in a marketplace or package registry. It is usually built from a publisher name and an extension name, and it acts as the extension’s stable identity for publishing, updating, searching, and trust tracking.
In cyber security, Extension IDs matter because attackers often target identity rather than code. A malicious actor may try to register a lookalike name, reclaim an abandoned namespace, or abuse a trusted ID to mislead users and internal tools. Defenders use Extension IDs to enforce allowlists, detect typosquatting, block known-bad artifacts, and preserve ownership history. Good registry hygiene treats an ID as more than a label: it is evidence of provenance, publisher control, and past abuse.