1. A system comprising: at least one processing device; and at least one computer-readable storage medium storing instructions which, when executed by the at least one processing device, cause the at least one processing device to: analyze a data stream having an associated data format, the data stream comprising an attack, generate multiple probes having multiple different values for multiple different data fields of the data format of the data stream, test for a vulnerability to the attack using the multiple probes, and generate an attack predicate for the vulnerability, the attack predicate comprising a conjunction of multiple conditions on the multiple data fields of the data stream, the attack predicate being generated by: relaxing a first condition of the multiple conditions, and relaxing a second condition of the multiple conditions.