Baslinux mailing list

[Matrix Mole <matrixm AT sdf.lonestar.org>]

On Sun, 29 Aug 2004, Ron Clarke wrote:

> > What does it mean to set user ID on execution?
>
>    That is the function in mc equivalent to chmod u+s [filename]

A more detailed answer is that when a program is set user ID on execution, 
it has the SUID bit set. What this does is when the program is actually 
run, it is ran as if started by the owner of the program instead of the 
user currently logged in. For some programs that need certain level of 
access to the filesystem, it's suggested that you SUID root for those 
programs (ensure that root is the owner of the file, then set the SUID bit 
on).

> > Is running links2 this way any more secure than running it as root?
>
>   I suspect it doesn't change anything else, but lets hear from the gurus.

With regards to security, the biggest difference is that you're not logged 
into the system as root itself. If there are vulnerabilities inherent in 
the program that can be taken advantage of by someone executing it as 
root, then it will have the same vulnerabilities when it has SUID root. 
The biggest vulnerability is if someone else had access to login to the 
machine and then execute a program that has SUID root, and manage to use 
that program to shell out to the command prompt (thus being shelled out as 
root). If you don't expect anyone else logging into the machine, then it's 
not that big a security risk.

--
Matrix Mole
matrixm AT sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org
Running BasicLinux error free since June 23, 2004