Date: Thu, 5 Jun 2008 12:15:16 +0200 From: Robert Buchholz <rbu@...too.org> To: oss-security@...ts.openwall.com Subject: Re: Python Unsafe Module Loading On Thursday 05 June 2008, Ned Ludd wrote: > 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 , 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 > > > >  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. The problem you demonstrated above was caused by (2), running a python script that is located in /tmp. Portage, and most other python programs, are not installed in /tmp, and therefore they do not import files from /tmp, even if they are actually called there: rbu@...nut /tmp $ touch re.so rbu@...nut /tmp $ cat /home/rbu/foo.py import string print "foo" import sys print sys.path rbu@...nut /tmp $ python /home/rbu/foo.py foo ['/home/rbu', '/usr/lib64/portage/pym', '/usr/lib64/python25.zip', '/usr/lib64/python2.5', '/usr/lib64/python2.5/plat-linux2', '/usr/lib64/python2.5/lib-tk', '/usr/lib64/python2.5/lib-dynload', '/usr/lib64/python2.5/site-packages', '/usr/lib64/python2.5/site-packages/Numeric', '/usr/lib64/python2.5/site-packages/gtk-2.0'] Robert Download attachment "signature.asc " of type "application/pgp-signature" (836 bytes)
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