oss-security - Re: Python Unsafe Module Loading

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Date: Thu, 05 Jun 2008 01:29:04 -0700
From: Ned Ludd <solar@...too.org>
To: Robert Buchholz <rbu@...too.org>
Cc: oss-security@...ts.openwall.com
Subject: Re: Python Unsafe Module Loading


On Thu, 2008-06-05 at 10:10 +0200, Robert Buchholz wrote:
> On Wednesday 04 June 2008, Ned Ludd wrote:
> > So for nearly every python based program you can simply dump  *.so
> > *.py *.pyc files just about anywhere on the file system where an
> > admin might invoke python.
> 
> As I also pointed out in our bug [1], this only happens in two cases:
> (1) The interactive shell is used to run python code.
> (2) A python script resides inside an untrusted directory.
> 
> What I expect to be the most common use case, running python code 
> from /usr, or /home, is safe. Since all out-of-the-box software would 
> be installed in directories that are not world-writable, I am tempted 
> call (2) an error on the user side. Changing the behaviour of python in 
> this manner would also break existing programs.
> 
> 
> Robert
> 
> [1] https://bugs.gentoo.org/show_bug.cgi?id=224925
> 


Re: (1)
How this limited to interactive shells? Our portage/emerge being 
directly not vuln is left to near sheer luck that Nick.C opted to shove 
a path into our portage module a-long time ago.. But our tools are 
questionable as it all depends on load order..

More examples:

solar@...ia /tmp $ touch re.so
solar@...ia /tmp $ cat foo.py 
import string
print "foo"

solar@...ia /tmp $ python foo.py
Traceback (most recent call last):
  File "foo.py", line 1, in ?
    import string
  File "/usr/lib/python2.4/string.py", line 83, in ?
    import re as _re
ImportError: /tmp/re.so: file too short
solar@...ia /tmp $ ls -l re.so 
-rw-r--r-- 1 solar solar 0 Jun  5 01:22 re.so

(2) yeah that's pretty much 50% of the problem.

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