1. A computer-implemented method for authenticating a user and user input to a back-end system and for validating the user input, the method being executed using one or more processors and comprising: receiving, by the one or more processors, a unique user identifier and user input; generating, by the one or more processors, a personalized image recognition challenge based on the unique user identifier and the user input, the personalized image recognition challenge comprising a plurality of images and a written message, the written message instructing a user to select a particular image of the plurality of images to validate the user input; transmitting the personalized image recognition challenge for display on a device; receiving, by the one or more processors, a response to the personalized image recognition challenge, the response comprising a selection of an image from the plurality of images; and authenticating the user and the user input based on the response.