Re: Positive uses for rootkits

[Cedric Blancher <blancher () CARTEL-INFO FR>]

On Wed, 21 Mar 2001 19:58:31 Daniel McCranie wrote:

> I was wondering that since intruders can modify system commands to
> not display certain things, couldn't admins modified the commands
> like cp, mv, rm...  so that they would not be able to replace any
> of the included commands?  These could be made in such a way only to
> work unlimited in single user mode or have the disk mounted to
> another system when there is a legitimate need to change one.

Changing programs is not sufficient, because you can't change every
executable that is reading filesystem for example. If you want to hide some
stuff, you'll have to act at kernel level.

> I have just enough UNIX knowledge to be dangerous to myself so be
> gentle :)
>
> Questions:
>
> 1. Are most rootkits simply shell scripts or real programs?

A rootkit is often a set of programs that aims to replace usual commands as
ls, ps, netstat and so on in order to hide some files, process,
connections, etc...
But you have "more clever" rootkit, such as modules which directly act on
inputs and outputs at kernel level.

> 2. Would there be anyway to stop programs from overwriting those
> files with programming calls?  (Maybe making them read-only and
> modifying chmod...)

Yes.
On Linux for exemple, you can use capabilities. LIDS security patch does
this and allows you to control each kernel system call.

> 3,4,5: I know that this probably wouldn't be good in a standard
> distro but what about a hardening kit?  Has this been tried before?
> Is there something blatantly wrong?

Have a look a LIDS for it is a great patch.

http://www.lids.org/

You can control almost everything. Have a look at the doc.

--
Cedric Blancher
Consultant securite systeme et reseau
Cartel Informatique
http://securite.cartel-info.fr/