OAuth/OIDC Assessment
Authentication done right—or exploited.
Authentication flow testing for OAuth 2.0 and OpenID Connect implementations, including token handling and redirect vulnerabilities.
Overview
OAuth 2.0 and OpenID Connect power authentication across the modern web, but their complexity creates opportunities for misconfiguration. Our OAuth/OIDC Assessment tests both your identity provider configuration and your application's implementation of these protocols, identifying vulnerabilities that could allow account takeover, privilege escalation, or data theft.
What We Test
Our oauth/oidc assessment engagements cover these key areas:
Redirect URI validation and open redirect vulnerabilities
Token handling (access, refresh, ID tokens)
State parameter implementation and CSRF protection
PKCE implementation for public clients
Scope enforcement and privilege escalation
Token storage, transmission, and expiration
Our Approach
OAuth vulnerabilities often exist in the subtle interactions between authorization servers, resource servers, and clients. We test each component and the flows between them.
Flow Analysis
Map all OAuth flows in use—authorization code, implicit, client credentials, device code. Understand how tokens are obtained, transmitted, and validated.
Redirect Testing
Test redirect_uri validation for open redirect vulnerabilities. Attempt subdomain matching bypass, path traversal, and fragment injection.
Token Analysis
Analyze token structure, signing, and encryption. Test for JWT vulnerabilities, token prediction, and insufficient entropy.
State/PKCE Testing
Verify CSRF protection through state parameter validation. Test PKCE implementation for code interception protection.
Scope Testing
Test scope enforcement on resource servers. Attempt to access resources beyond granted scopes and test for scope manipulation.
Token Lifecycle Testing
Test token expiration, revocation, and refresh mechanisms. Verify that revoked tokens are actually rejected and refresh tokens are properly protected.
Common Findings
These are issues we frequently discover during oauth/oidc assessment engagements:
Open redirect via redirect_uri
Weak redirect URI validation allows attackers to redirect authorization codes or tokens to attacker-controlled servers, enabling account takeover.
Missing state parameter
OAuth flows without state parameter validation are vulnerable to CSRF, allowing attackers to force users to link accounts or grant unintended access.
Insufficient scope validation
Resource servers don't properly validate token scopes, allowing tokens with limited scopes to access protected resources.
Token leakage in logs/URLs
Access tokens or refresh tokens exposed in URL parameters, referrer headers, or application logs where they can be captured by attackers.
Missing PKCE on mobile apps
Mobile applications using authorization code flow without PKCE are vulnerable to authorization code interception by malicious apps.
Common Questions
Do you test identity providers we don't control?
We focus on your application's implementation—how you handle tokens, validate responses, and protect user sessions. We can't test third-party IdP infrastructure (Google, Okta, etc.) but we can test your integration with them.
Should we still use the implicit flow?
No. The implicit flow is deprecated for most use cases. Authorization code flow with PKCE is recommended for all clients, including SPAs and mobile apps. We can help you migrate if you're still using implicit.
What about refresh token rotation?
We test whether refresh token rotation is implemented and enforced. Rotation limits the damage from token theft but must be implemented correctly to be effective.
Do you test custom OAuth implementations?
Yes, and we pay extra attention to them. Custom OAuth implementations often have subtle bugs that standard libraries avoid. We've found significant vulnerabilities in homegrown OAuth servers.
Other API Security Testing Options
REST API Testing
Comprehensive testing of RESTful APIs for authentication bypass, injection flaws, broken object-level authorization, and data exposure.
GraphQL Security
Specialized testing for GraphQL APIs including introspection attacks, query complexity abuse, and authorization bypass.
SOAP/XML Services
Legacy web service testing for XML injection, SOAP action spoofing, and WS-Security implementation flaws.
Mobile Backend APIs
Testing APIs that support mobile applications, focusing on certificate pinning bypass, API key exposure, and mobile-specific attack vectors.
Ready to Strengthen Your Defenses?
Schedule a free consultation with our security experts to discuss your organization's needs.
Or call us directly at (445) 273-2873