Summary
Typemill's primary login endpoint does not limit failed password attempts when captcha protection is disabled, which is the default configuration. An unauthenticated attacker may submit unlimited guesses against user or administrator accounts without throttling or lockout.
Affected context
The weakness occurs in Typemill's web authentication flow at POST /tm/login, handled by ControllerWebAuth::login(). It is most relevant when captcha is disabled and the primary password-authentication path is exposed to unauthenticated clients; protections associated with the optional secondary email-authcode step do not cover password attempts.
Exploit preconditions
- Attack surface: Publicly reachable Typemill login endpoint
- Required access: No authentication is required before submitting login attempts
- Trigger point: Repeated failed password checks through
POST /tm/login - Why exploitation is possible: The primary password path lacks rate limiting, failed-attempt accounting, and account lockout when captcha is disabled
Why this happens
The authentication controller does not apply an attempt-management policy to the primary password verification process. Although related counting and lockout logic exists for an optional email-authcode step, that control is not shared with or enforced for password authentication. This maps to CWE-307: Improper Restriction of Excessive Authentication Attempts, because the application permits repeated authentication failures without effective throttling or lockout.
Potential impact
- An attacker may guess weak or reused passwords
- User accounts could be taken over
- Administrator accounts may be compromised
- Compromised accounts could be used to alter content or application settings
- Successful attacks could enable further access depending on account privileges
General mitigation guidance
Mitigation generally focuses on enforcing consistent authentication-attempt controls across every login method.
Common defensive patterns include:
- Apply server-side rate limiting to password authentication by account, source, and other risk-aware signals
- Track failed attempts for the primary password flow and use bounded, temporary lockouts or progressive delays
- Keep challenge mechanisms enabled where appropriate, while treating them as an additional control rather than the sole defense
- Use secure password policies and multi-factor authentication for privileged accounts
- Avoid relying on client-side controls or controls that apply only to secondary authentication steps
- Run administrative accounts with least privilege and monitor unusual authentication activity
How teams detect issues like this
Organizations can identify this weakness through:
- Static analysis and code review checks for login handlers lacking throttling, failure counters, or lockout enforcement
- Tests that submit repeated invalid credentials and verify bounded response behavior
- Policy checks requiring brute-force protections on every password-authentication endpoint
- Monitoring for bursts of failed logins across individual accounts, source addresses, and distributed sources
- Automated security testing or code-review tools that flag authentication flows without attempt restrictions
