Building a safe, effective sandbox to enable Codex on Windows

The Codex engineering team faced a challenge in implementing a secure sandbox on Windows, as existing native tools like AppContainer and Windows Sandbox were ill-suited for open-ended developer workflows. Initially, the team prototyped an unelevated sandbox using synthetic SIDs and write-restricted tokens; however, this lacked robust network isolation. The final architecture, an 'elevated sandbox,' uses dedicated local Windows users, granular firewall rules, and a multi-binary system to securely restrict file writes and network access while maintaining high developer productivity. This design balances the need for agent autonomy with essential system security.

(Source：OpenAI)