Re: Linux login security approaches

thomasz@hostmaster.org
Tue, 8 Dec 1998 00:33:47 +0100


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> Some hours ago we had a discuss on Linux security, here at the University.
> I mentioned that Linux has got a weak point : every user can write a fake
> login program and even the system administrator can think that it's mgetty
> and type the root password :( This kind of Trojan programs can be precede=
d.
> We should define a key combination which is unmaskable by ANY process, and
> login procedures should begin by pressing this combo. However I was told =
that
> this is "an NT way" solution, but I disagree. (I don't know anything on
> NT before I've hopefully never used it :) But the idea is great. The fact

This is a required feature for C2 level security certification.
Microsoft used to use the Ctrl-Alt-Del combo in Windows NT because it trigg=
ers an unmaskable interrupt.
This feature will be gone in Windows NT Workstation 5.0 (2000).
I believe that linux can do special processing for any combo.
You could either use existing Magic SysRQ functionality: Alr-SysRq-k or wri=
te a simple program which captures the Ctrl-Alt-Del combo via init and kill=
s all processes assigned to the current VC (don=B4t know how to figure out).
In either way you introduce a big insecurity because programs like vlock or=
xlock won=B4t be reliable any longer (the same problem as in Win3 beta).

Thomas

-------------------------------------------------
T h o m a s Z e h e t b a u e r ( TZ251 )
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