shars and security concerns.

[Tom Neff]

In article <FAIGIN.90May2120834 at sunstroke.aerospace.aero.org> faigin at aerospace.aero.org (Daniel P. Faigin) writes:
>There are still major security concerns about this. Suppose you had an unshar
>program that only allowed cat and chmod. That's it. You still have risks...
 ^^^^^^^

You need have no more risks than the unshar program is willing to allow.
It could prevent setuid stuff, writing out of the current subtree, etc.

>Shars are dangerous, and unshar programs don't get around the problem.
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This doesn't take my previous proposal into account.  (Did the poster
read it?)  If standardized header information were provided as shell
#comments, then an also-standardized unshar program could read a shar as
effortlessly as a tar file, and with equally faithful results.  Under
this scheme there would be no "operations" at all, just file and
directory creation.  By imposing appropriate limits on what "Mode=" and
"Name=" is allowed to be, unshar could operate safely.