Problems with turning off setuid

[utzoo!decvax!ucbvax!unix-wizards]

>From MathStat.jmrubin at Berkeley Sat Sep 12 00:52:45 1981
	From csvax:unix-wizards Fri Sep 11 21:23:14 1981
	Subject: Problems with turning off setuid
	Newsgroups: fa.unix-wizards
	>From decvax!duke!unc!smb at Berkeley Fri Sep 11 21:04:18 1981
	In-real-life: Steven M. Bellovin
	Location: University of North Carolina at Chapel Hill
	
	Although I feel that Berkeley's practice is indeed a reasonable
	protection scheme, it can cause problems.  For example, I sometimes
	create setuid programs that have group-write permission.  To test a
	new version, I can just copy the file into it, without having to 'su'
	each time.  Assuming that /etc/group is secure (or no less secure than
	/etc/passwd, at any rate), there is no security risk.
	
	
	I don't think that group security is as strong as individual security.
On at least some systems, the empty core-dump from a setgid program can be
made into a setgid program to fork a shell.  (or do anything else)
Thus, if you have this system, you may give someone the total
permissions which the owner of the setuid program has.

	By the way, we seem to be getting all messages from Steven Bellovin
in duplicate or triplicate.  Anyone know why?
					Joel Rubin