gcc can also be used for file read

[NQNStudios]

While doing the challenges for the first module of pwn.college I found a way to read files with an SUID version of gcc.

Following the format of other examples, this is how to reproduce:

sudo sh -c 'cp $(which gcc) .; chmod +s ./gcc'

LFILE=file_to_read
./gcc -x c "$LFILE"

Assuming the privileged file is not valid C code, much if not all of its lines should be output within syntax error messages.

Is this the kind of example that would be worth adding?

[cyrus-and]

While this might work to read files in general, it fails when SUID with:

gcc: error trying to exec 'cc1': execvp: No such file or directory

I assume that in a system that, for whatever reason, allows to run gcc as SUID this is already taken care of... but anyway, let's just add the file-read function.

Is this the kind of example that would be worth adding?

Yes, please open a PR, we'll resume from that. Thanks!