Notes about Python Security.
tav's jail
http://tav.espians.com/a-challenge-to-break-python-security.html
Remove evil attributes like frame.f_globals or object.subclasses
- Remove evil builtins like compile(), import() or reload()
Zope security
http://svn.zope.org/zope.security/trunk/src/zope/security/
- Sandboxing
- Object proxies
Taint mode
Nicole King (cats-muvva.net) wrote a taint mode for CPython 3.0: Python Taint Management.
Problems:
amaury: The patch is indeed huge!
fijall: it seems that every function that returns a PyObject must be modified
fijall: need to patch (...) all places that might modify anything. (All side effects)
=> ncoghlan: PyPy is still a *much* better platform for that kind of experimentation than CPython
See also the presentation: Securing Python: Controling the abilities of the interpreter, PyCon US 2007, Brett Cannon and Eric Wohlstadter
Related issue: Taint a la Perl?.
Python Security Response Team
Some members:
- Brett Cannon
Email: security AT python.org
Controlling Access to Resources Within The Python Interpreter
Paper: Controlling Access to Resources Within The Python Interpreter, Brett Cannon and Eric Wohlstadter, University of British Columbia
Sandboxing
PyPy project: PyPy's sandboxing features.
CapPython is an object-capability subset of Python, inspired by Joe-E and Caja/Cajita, which are object-capability subsets of Java and Javascript respectively.
How can I run an untrusted Python script safely (i.e. Sandbox)
Unsafe modules
- os.kill(), os.chown(), os.unlink(), ...
- imageop: many bugs
CVE-2007-4965: Integer overflow in imageop module (2007-09 .. 2008-08)
Buffer overflow in imageop module (rgb2rgb8): fixed in Python 2.6.1 and Python 3.0
Restricted
- Deprecated (disabled?) since Python 2.3
Fuzzing
Victor Stinner wrote a fuzzer called Fusil to test Python. It already helped to fix many bugs. fusil-python works on Python 2.4 .. 3.0.
Fusil was also used on PyPy (Finding Bugs in PyPy with a Fuzzer).