The rule "Auth0: Excessive Login Failures or Signups" is designed to detect potential credential stuffing or brute-force attacks targeting authentication endpoints of applications that utilize Auth0 for user management. It does so by monitoring authentication logs for IP addresses that have been blocked due to an excessive number of failed login or signup attempts. When a certain threshold of unsuccessful attempts is reached, Auth0 responds by blocking further requests from that IP address, which is indicative of automated attack vectors, such as a threat actor trying to gain unauthorized access through credential guessing techniques. The detection logic leverages the `get_authentication_data_auth0` function in Splunk to filter for relevant events characterized as "limit_mu" which denote that the IP's actions have triggered a rate limit or block. The data analyzed includes event timestamps, host identifiers, user information, geographical location data, and source IP addresses. This rule is crucial for protecting against automated account takeover attempts and mitigating risks associated with unresolved potential breaches.