A historical repository of UE identifiers associated with sets of prior mean values and prior standard deviation values, is maintained. A browser request message is received from a web browser on a suspect UE and requests access to an electronic resource. An identification challenge message is sent toward the web browser and contains a hash script configured to be processed by the web browser to hash a challenge data set and to report a measurement of elapsed hashing time. A device identification report is received from the web browser and contains a terminal signature tuple of a reported UE identifier and the elapsed hashing time. A posterior probability value indicating a likelihood that the suspect UE corresponds to a genuine UE identified by the reported UE identifier, is generated. Whether the suspect UE is permitted to access the electronic resource is controlled based on the posterior probability value.