A method and system for associating a unique device identifier with a potential security threat are described. In a method conducted at a remotely accessible server, a unique device identifier is received from a computing device. The unique device identifier is associated with a record and is usable in identifying the computing device. An interaction data element is received from the computing device. The received interaction data element is validated including confirming that the received interaction data element matches an expected interaction data element associated with the record. Based on determining that the received interaction data element is not valid, the record is updated to associate the unique device identifier with a potential security threat. The interaction data element is updated periodically according to a sequence. The expected interaction data element changes based on the sequence.