1. Use Strong Passwords

   • Enforce strong password policies. Use a password strength checker like zxcvbn to guide users in creating secure passwords.
   • Example: If a user tries "password123," the system should suggest using "MyStr0ng#Pass2025" instead.

2. Prevent Username Enumeration

   • Return the same error message and HTTP status code for invalid usernames and passwords to avoid revealing whether a username exists.
   • Example: Show "Invalid credentials" for both wrong usernames and passwords, without confirming which part was incorrect.

3. Implement Account Locking

   • Temporarily lock accounts after a certain number of failed login attempts.
   • Example: Lock an account for 10 minutes after 5 wrong attempts to prevent targeted brute-forcing.

4. Limit Login Attempts (Rate Limiting)

   • Limit login attempts per IP address and block suspicious behavior.
   • Example: Allow 5 attempts per minute per IP. Block further attempts for 15 minutes if the limit is exceeded.

5. Add CAPTCHA for Extra Protection

   • Require users to complete a CAPTCHA after several failed login attempts.
   • Example: After 3 failed logins, show a CAPTCHA like "Click all the images with traffic lights."

6. Implement Multi-Factor Authentication (MFA)

   • Use app-based or hardware-based MFA instead of SMS.
   • Example: After entering a password, require a 6-digit code from Google Authenticator or a similar app.

7. Secure Password Reset

   • Use a time-limited, unique token for password reset links.
   • Example: Send an email with a link that expires in 15 minutes. Ensure the link can only be used once.

8. Avoid SMS-Based MFA

   • SMS 2FA can be bypassed via SIM-swapping attacks. Use app-based authentication instead.
   • Example: Encourage users to set up an authenticator app for 2FA instead of relying on SMS codes.

9. Protect Additional Authentication Functions

   • Secure features like account registration, password recovery, and password changes.
   • Example: Require users to verify their email before changing their password.

10. Prevent Brute-Force Attacks on Multiple Accounts

    • Limit the number of login attempts across all usernames using shortlists of passwords.
    • Example: If an attacker tries common passwords like "123456" or "qwerty" across accounts, block them after 5 attempts.

11. Triple-Check Verification Logic

    • Regularly audit login and authentication logic to prevent bypass vulnerabilities.
    • Example: Ensure the system verifies both the username and password properly and doesn't skip steps due to flawed code.

12. Don’t Rely on Users for Security

    • Enforce secure practices like strong passwords and MFA automatically.
    • Example: Block weak passwords like "Password123" and require a unique, strong password.

13. Implement Robust Brute-Force Protections

    • Require CAPTCHA or other verification methods after multiple failed attempts.
    • Example: After 5 failed attempts from the same IP, show a CAPTCHA and notify the account owner.

Please feel free to add more :).

Acknowledgment: This document references information from PortSwigger Web Security