Systems and methods for detecting attacks using a handshake request are provided. A plurality of devices can receive a plurality of handshake requests to establish TLS connections that include a respective application request. At least one of the plurality of handshake requests can include a first application request. The plurality of devices can record each of the respective application requests to a registry of application requests. A first device of the plurality of devices can receive a subsequent handshake request to establish a subsequent TLS connection that includes the first application request. The first device can query, prior to accepting the first application request, the registry for the first application request. The first device can determine whether to accept or reject the first application request responsive to identifying from the query that the first application request has not been or has been recorded in the registry.