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From: tr@samadams.princeton.edu (Tom Reingold)
Newsgroups: alt.hackers
Subject: Re: Execute only files on Novell
Message-ID: <224@rossignol.Princeton.EDU>
Date: 7 Jun 90 23:34:47 GMT
References: <445@ria.ccs.uwo.ca>
Sender: news@cs.Princeton.EDU
Organization: Princeton University, NJ
Lines: 36
Approved: me (him)

In article <445@ria.ccs.uwo.ca> pruss@ria.ccs.uwo.ca (? pruss) writes:
$ The Execute-Only attribute in Novell netware seems to be rather
$ poorly implemented.  While much care is put into making certain
$ that the attribute is permanent and cannot be revoked by any user
$ (not even supervisor), with a little care and ingenuity any 
$ JoeHacker-User with execute priveleges to that file can copy it.
$ 
$ In fact I have even been able to write a program that makes it possible
$ for any user to run it and subsequently copy ANY exec-only file.
$ 
$ Please note I have distributed neither my program nor specific data
$ on how this is done.
$ 
$ The cause of this security gap seems to be the fact that for exec-only
$ files the server queries the workstation whether it is executing
$ the program and thus is allowed to read it, or whether it is just reading it.
$ The workstation can, of course lie...  
$ 
$ I am wondering whether any one has hacked netware to make exec-only
$ more secure?

This is probably a "hard" problem to solve.  There is no notion of
network security, only security on machines.  So once a message gets to
the network, it is assumed to be authoritative.

I have read that the same problem exists in NFS.  Superuser must have
read access to a file in order to load it into memory, at least in
theory.  So to execute a file, you have to "copy" it into memory.  If
Superuser on a machine can read it, how are you going to prevent Joe
User from having less access than Superuser if the authentication is
done on the network?
--
                                        Tom Reingold
                                        tr@samadams.princeton.edu
                                        rutgers!princeton!samadams!tr
                                        201-560-6082