Fuzzing encoded data

One or more volatile and/or non-volatile computer readable media storing information to enable a computer to run a software testing tool to perform a process of fuzzing a test file to be used to test an application, the process comprising:

• accessing the test file, the test file containing structured content, the structured content comprising a plurality of fields formatted and arranged in accordance with a pre-defined format that the application is configured to parse, the content including at least a first field containing a second field, the first field and second fields having been encoded as a group with an encoding algorithm, where other parts of the structured content are not encoded by the encoding algorithm;
• identifying the encoding algorithm and in accordance therewith decoding as a group the first and second fields and fuzzing the decoded second field but not the first field;
• encoding as a group the first and second fields with an encoding algorithm corresponding to the decoding algorithm and generating a fuzzed test file by replacing in the test file the original encoded first and second fields with the encoded first field and fuzzed second field;
• and
• testing the application by processing the fuzzed test field with the application.

A computing device configured to be capable of performing a process for fuzz-testing a computer program, the process comprising:

• preparing input data for fuzz-testing the computer program by:
• parsing original input data to identify a field therein, the input data comprising valid input for the software application, the input data comprising a plurality of discrete fields and values therein, wherein the identified field is in encoded form such that substantive content of the field cannot be accessed without decoding the identified field, the identified field being in encoded form in the input data, the identified field having been encoded by a particular encoding algorithm, the other fields not having been encoded by the encoding algorithm;
• decoding the selected field element of the input data using a decoding algorithm corresponding to the encoding algorithm;
• performing a fuzzing operation on the decoded data field and then encoding the data field with the encoding algorithm;
• and
• storing input data including the fuzzed and encoded data field.