I realize writing up every Protostar/Phoenix exercise has been done a million times over, but this is for my own notes and to track my progress.
Stack Zero is a classic buffer overflow. With the source code handy, we can see there is a buffer of 64 characters and the method gets is used:
locals.changeme is set to anything other than 1, we get a success. This is easy to accomplish via printing 65 A’s and providing them as input:
And we get a success: