4.1.1 Establish the authentication technologies in use (for example, forms, certificates, or multifactor).
4.1.2 Locate all the authentication-related functionality (including login, registration, account recovery, and so on).
4.1.3 If the application does not implement an automated self-registration mechanism, determine whether any other means exists of obtaining several user accounts.
4.2.1 Review the application for any description of the minimum quality rules enforced on user passwords.
4.2.2 Attempt to set various kinds of weak passwords, using any self-registration or password change functions to establish the rules actually enforced. Try short passwords, alphabetic characters only, single-case characters only, dictionary words, and the current username.
4.2.3 Test for incomplete validation of credentials. Set a strong and complex password (for example, 12 characters with mixed-case letters, numerals, and typographic characters). Attempt to log in using different variations on this password, by removing the last character, by changing a character's case, and by removing any special characters. If any of these login attempts is successful, continue experimenting systematically to identify what validation is actually being performed.