This describes a program (afl) which is given another program (djpeg, some kind of JPEG parser - takes arbitrary data and decides if its JPEG or not) to play with.
afl starts feeding it random inputs gradually gaining limited understanding about what it accepts and what it does not.
Eventually, it gathers enough info (based on strace'ing, google it, and its output) to start pulling JPEG images out of thin air like it's nothing.
The catch is, that this afl program learns this all by itself, and it can do so with any other parser program (like ELF parsers, GIF parsers, whatever). It is a general purpose tool.
Also, similar concept can be applied to things like web servers, or any other servers (since they parse what clients send them).
afl starts feeding it random inputs gradually gaining limited understanding about what it accepts and what it does not.
Eventually, it gathers enough info (based on strace'ing, google it, and its output) to start pulling JPEG images out of thin air like it's nothing.
The catch is, that this afl program learns this all by itself, and it can do so with any other parser program (like ELF parsers, GIF parsers, whatever). It is a general purpose tool.
Also, similar concept can be applied to things like web servers, or any other servers (since they parse what clients send them).