Re: Mounting PC Floppy Disks - Summary

From: Sjoerd Mullender (Sjoerd.Mullender@cwi.nl)
Date: Fri Mar 27 1992 - 11:19:21 CST


I know I shouldn't reply to the list, but I believe this is important
for everyone who read the original message.

On Tue, Mar 24 1992 Bryan Emery wrote:

> From: simon%gpsemi.COM (Simon Booth x8125 System Mangler ! - Unix)
  [stuff deleted]
> The mount script ( Call it for eg mountfd ) :
  [stuff deleted]
> #! /bin/csh -b
> #
> # Set UID root script
  [stuff deleted]
> (The -b is importanmt in the first line )
  [stuff deleted]
> The unmount script ( eg umountfd )
>
> #! /bin/csh -b
> #
> # Set UID root script
  [stuff deleted]

Do not install these scripts. There is a inherent security risk in
setuid shell scripts, whether they be for sh or for csh or for any
other interpreter. Given a setuid script it is trivial to become root
(if you know how) and there is nothing you can do to prevent that.
Make a C program instead that does what the script is supposed to do.

Sjoerd Mullender
CWI, dept. CST, Kruislaan 413, 1098 SJ Amsterdam, Netherlands
email: Sjoerd.Mullender@cwi.nl fax: +31 20 592 4199
phone: +31 20 592 4127 telex: 12571 mactr nl



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