* fix(backend): reject a replayed TOTP code within its validity window
verifyTotp() was stateless — otplib's window:1 tolerance meant the
same 6-digit code could complete two independent logins inside its
~90s validity window. Track each admin's last-consumed step and
reject a code that doesn't advance past it.
* fix(backend): make the TOTP replay-tracking persist atomic
verifyTotpEncryptedStep() read two_factor_last_used_step, then a plain
UPDATE wrote the new step with no conditional guard — two concurrent
requests carrying the same captured code could both pass the check
before either UPDATE landed. The persist is now a conditional UPDATE
(only advances the step, checked via affected-row count), so a losing
concurrent request is correctly treated as a replay.
---------
Co-authored-by: Paul Nothaft <paul@MacStudio-von-Paul.local>
Backend for #738. Real TOTP 2FA for admin accounts, all roles incl.
super_admin (closes#735).
- mfaService: otplib TOTP; AES-256-GCM encryption of the secret at rest
(key derived from MFA_ENCRYPTION_KEY or JWT_SECRET); bcrypt-hashed,
single-use recovery codes; otpauth URI + QR.
- Migration 151: adds two_factor_recovery_codes + two_factor_enrolled_at
(secret/enabled columns already existed from legacy 016).
- Enrollment endpoints (behind adminAuth, per-user): GET /mfa/status,
POST /mfa/{setup,enable,disable,recovery-codes}. Disable/regenerate
require a current code so a hijacked session can't strip 2FA.
- Login challenge: /admin/login returns {mfaRequired, mfaToken} (no
session) when 2FA is on; /admin/login/mfa exchanges a TOTP or recovery
code for the session. Lockout counter is NOT reset until the second
factor passes, so MFA brute-force is rate-limited too.
- CLI break-glass: scripts/reset-admin-mfa.js --email <e> | --all --yes,
audit-logged, matches reset-admin-password.js convention.
- Docs + optional MFA_ENCRYPTION_KEY env.
Verified end-to-end on a live backend: enroll (super_admin), challenge,
TOTP + single-use recovery login, disable, and CLI reset.
Paul Nothaft