Systems and methods for detecting abnormal user activity comprising: tracking, by the server, during a first time period, user activity associated with an application service, determining, by the server, that the user activity associated with the application service exceeds a respective first predetermined threshold of user activity during the first time period, in response to determining that the user activity exceeds the first predetermined threshold, tracking, during a second time period user activity associated with the application service, the tracking comprising tracking a content of the user interactions with the application service, determining that the user activity exceeds a second predetermined threshold of user activity during the second time period and in response to determining that the user activity exceeds the second predetermined threshold, triggering a user challenge procedure on a client device.