Enforcing sensitive data protection in security systems

A security system that monitors requests to a protected resource is configured to determine that a syntactically-invalid language statement in a request is one that should be treated as a “security high risk” statement (SHRS) because it has a probability of containing sensitive data. A machine language that defines the structure and syntax of the language statements used by a client-server application may have multiple SHRSs. SHRSs are identified in advance by syntactical analysis of the language statements that comprise the machine language. The security system stores (or can otherwise obtain) a representation of each of the set of these high risk statements. In response to detecting that a request has a syntactically-invalid language statement, the system determines whether the invalid language statement has a measure of similarity sufficiently close to any of statement in the SHRS set. Upon a positive determination, an appropriate security action is taken to ensure sensitive data is not exposed.