RE: Disabling module loading with a module?

Matthew Kirkwood (weejock@ferret.lmh.ox.ac.uk)
Tue, 17 Aug 1999 15:05:05 +0100 (GMT)


On Tue, 17 Aug 1999, Jones D (ISaCS) wrote:

> The attack would have gained root. He could 'exec rm -rf /' or fdisk,
> or 'cat /dev/random > /dev/sda', or _anything_ else.

No. Go read the securelevel code in 2.0. The highest securelevel (3,
I think) bans writes to block devices. I think that it also blocks
mount calls, so read-only filesystems would be protected, too.

> Disabling modules interface won't stop bad people doing bad things.

No. Examine securelevels or the capability stuff (esp. the securelevel-
like bounding set) in 2.2+. root's power can be constrained. It _does_
stop people doing bad things.

> It will just stop good people doing anything productive.

> Time would be better spent improving security elsewhere.

Why? If I can disable module loading, promiscuous network operation and
a few nasty filesystem things _even for root_ then the risk to my network
of a compromised machine is greatly reduced.

> Instead of thinking of ways to stop people doing things when they get in,
> stop them getting in in the first place..

Following that argument, perhaps I should run Apache as root? Oracle?

Matthew.

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