pickle and security

[Martin v. Löwis]

Ben Hutchings <do-not-spam-ben.hutchings at businesswebsoftware.com> writes:

> > Depending on your version of cPickle, it also contains a call to eval,
> > to unpickle a string. This is believed to be safe (as only safe
> > strings are passed to eval), but you may want to review that specific
> > fragment of code.
> 
> What about the attack suggested in
> <mailman.1049909846.24938.python-list at python.org> (which is to use
> "".__class__.__class__.__subclasses__("".__class__.__base__) to access
> supposedly inaccessible classes)?

It is unrelated to the context of my posting, as you cannot exploit
this in the eval calls that pickle/cPickle do.

I believe you can also not exploit this in pickle at all, since you
cannot have pickle perform arbitrary getattrs on unpickling.

Regards,
Martin