[Python-Dev] Challenge: Please break this! (was: Reviving restricted mode) (original) (raw)

Guido van Rossum guido at python.org
Mon Feb 23 22:38:21 CET 2009

On Mon, Feb 23, 2009 at 1:36 PM, Guido van Rossum <guido at python.org> wrote:

On Mon, Feb 23, 2009 at 1:12 PM, Victor Stinner <victor.stinner at haypocalc.com> wrote:

The challenge is simple:

* Open a fresh Python interpreter * Do: >>> from safelite import FileReader * You can use FileReader to read files on your filesystem * Now find a way to write to the filesystem from your interpreter Well, the challenge is to get access to a module. And... it's quite simple :-p $ ./python from safelite import FileReader builtins.file Traceback (most recent call last): File "", line 1, in AttributeError: 'module' object has no attribute 'file' reload(builtins) <module '_builtin_' (built-in)> file('0wn3d', 'w').write('w00t\n')

$ cat 0wn3d w00t Dinner and drinks on me for an evening -- when you are next in London or I am in your town -- to the first person who manages to break safelite.py and write to the filesystem. Cool. It's a good reason to go to Pycon UK this yeak ;-) Tav should have made another stipulation: the attack must not be trivial to fix. This one seems trivial, e.g. by adding 'reload' to the list in securepythonbuiltins().

I take it back, we need to find all the trivial ones too.

BTW Tav, you ought to create a small website for this challenge. A blog post or wiki page would suffice.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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