Authentication and session security testing
Broken authentication is anything that lets an attacker become another user — a weak or leaked session, a guessable password reset, a login with no rate limiting, an MFA step the server never actually enforces. Sintropyc tests your login, session and account-recovery flows end to end and proves each weakness that matters.
What authentication testing covers
- Login — credential-stuffing and brute-force resistance, rate limiting, username enumeration
- Sessions — token strength, fixation, expiry, invalidation on logout and password change
- Password reset — guessable or reusable tokens, host-header poisoning, tokens that don't expire
- MFA / OTP — steps the client shows but the server doesn't enforce, code brute-forcing, bypass via a parallel endpoint
- OAuth / SSO — redirect and state handling, token validation
The quiet failures that matter most
The dangerous authentication bugs aren't the obvious ones. A reset token that never expires, a session that survives a password change, an OTP the API accepts even when the UI didn't ask for it — each looks fine in normal use and hands over accounts in the wrong hands.
A missing rate-limit header means little on its own. Sintropyc confirms the real weakness — that codes can actually be brute-forced, or a session actually survives when it shouldn't — before reporting it.
How Sintropyc tests it
Sintropyc is an autonomous AI penetration testing agent. It signs in as real users across different roles, drives your product the way a customer would, and proves every finding with a working exploit — never a scanner guess. Each finding is checked by a human before it reaches you, comes with the exact fix, and is attacked again after you ship it to confirm it held.
For authentication, Sintropyc exercises the real flows with real accounts — logging in, resetting passwords, stepping through MFA, refreshing and revoking sessions — and probes each for a concrete bypass. It reports a finding only when it can demonstrate the effect: an accepted code it shouldn't be, a session that stays valid, an account reachable without the right factor.
What you get
- Login, session, reset and MFA flows tested for real bypasses
- Each finding demonstrated, not inferred from a missing header
- The exact fix (server-side enforcement, token handling, rate limits)
- A retest after you ship it
Common questions
Do you test our OTP / 2FA?
Yes. A common real bug is an OTP or MFA step the frontend shows but the API doesn't enforce — Sintropyc checks whether the server truly requires each factor, and whether codes can be brute-forced.
Will brute-force tests lock out real users?
No. Rate-limit tests use throwaway test accounts and controlled volumes; we never run credential attacks against your real users.
Do you cover JWT issues?
Yes — token forgery, weak signing and expiry are covered here and in more depth on JWT security testing.