OAuth 2.0

Overview

OAuth 2.0 is an authorization framework that lets a client obtain limited access to an HTTP service without receiving the resource owner’s password. OAuth 2.0 delegates authorization; it is not by itself an identity protocol, although OpenID Connect can add authentication on top of it.

Key risks include token theft, redirect manipulation, authorization-code interception, insecure client authentication, excessive scopes, replay, and confusion between clients or authorization servers. The OAuth 2.0 recovery process should restore access without bypassing the original identity and authorization controls.

A production implementation should select a suitable grant, use exact redirect URI matching, protect tokens, apply PKCE where applicable, validate issuer and audience, and follow the current OAuth security best practices. Evidence for OAuth 2.0 should record the credential or certificate identifier and decision result without retaining the secret itself.

Useful measures include authorization success rate, token error rate, rejected redirect attempts, scope usage, token lifetime, refresh failures, and suspicious replay indicators. OAuth 2.0 is closely connected to Authorization Endpoint, Client ID, and OAuth Token Exchange. Monitoring for OAuth 2.0 should track failed use, unusual scope or audience, expiry, rotation status, and attempts involving revoked credentials.

The OAuth 2.0 boundary should identify the principal, credential or key, permitted audience, scope, lifetime, and revocation path. For OAuth 2.0, secrets and tokens should remain outside browser bundles, URLs, ordinary logs, and unprotected configuration.

Changes to OAuth 2.0 should preserve overlap or recovery where required while preventing old credentials from remaining active indefinitely.