The disclosed embodiments provide a system that facilitates testing of an insecure computing environment. During operation, the system obtains a real data set comprising a set of data strings. Next, the system determines a set of frequency distributions associated with the set of data strings. The system then generates a test data set from the real data set, wherein the test data set comprises a set of random data strings that conforms to the set of frequency distributions. Finally, the system tests the insecure computing environment using the test data set.