Fuzzing PDFs like its 1990s

This is the fuzzer I made to fuzz Preview on macOS and iOS like 8years back when I just started fuzzing things.

Some disclosed vulnerabilities:

• CVE-2015-3723
• CVE-2016-1737
• CVE-2016-1740
• CVE-2017-7031

The basic idea of this fuzzer was to mutate the streams of the pdf files without screwing the PDF Structure as a whole. I collected some hundreds of PDFs and converted the PDFs to Python script using Didier Stevens’s pdf-parser -g flag. The fuzzer uses cPDF that I modified to mutate the stream using Charlie’s 10liner, every time I try to generate a PDF file.

This made it really easy to mutate the stream and create the PDF file from the fuzzing server.

I used Charlie’s 10liner for mutations: