Service data is received by a server and from a client computing device, where the service data includes a unique identifier and a variable identifier stored in a local secure storage of the client computing device. The server parses the service data to obtain the unique identifier and the variable identifier as parsed data. The server determines whether the unique identifier and the variable identifier in the parsed data are identical to a unique identifier and a variable identifier associated with the client computing device and recorded by the server as recorded data. If the result of the determination is not identical, the server indicates that the local secure storage of the client computing device is under a copy attack, and performing a predetermined response action. If the result of the determination is identical, the server transmits a new variable identifier to the client computing device.