From: Michal Suchanek <hramrach@...>
Date: 2011-10-25T08:08:12+09:00
Subject: Re: security thesis advice

On 25 October 2011 00:53, Christian Pedaschus <chris@s-4-u.net> wrote:
> On 10/25/2011 12:30 AM, Jorge Bo wrote:
>> Hi Chris, thanks for your answer
>>
>> Honestly, im just evaluating different approaches.I'm finding very
>> interesting the Ruby metaprogramming model,i posted a crazy idea in a
>> previous message yesterday, that was crossing my mind, but it seems to be
>> imposible to achive. But it could serve as a point of start.
> I've read your proposal, and it immediatelly reminded me about openbsd's
> securelevel(7). Wouldn't Openbsd count as an example, where a
> potentially unsafe system is booted, and secured it has booted? Doesn't
> it all depend on the kernel/interpreter?
>
> Compare:
>  http://www.openbsd.org/cgi-bin/man.cgi?query=securelevel&sektion=7
> With:
>  http://www.rubycentral.com/pickaxe/taint.html
>
> For me, it sounds quite comparable, 'same old procedure', and the same
> result: "start an untrusted system and secure it afterwards...
>
> Or am i missing something? (right now, that's quite possible *lol*)

Yes, there some things that you are missing.

While the OpenBSD secure levels aren't very good security mechanism
you missed a few important points.

1) You boot a trusted system, not an untrusted one. Booting untrusted
system is quite pointless.

2) You enter a higher secure level before allowing access from the
outside. The securing is pre-emptive, not reactive as in the proposal.

Thanks

Michal