Re: How T-Mobil's network was compromised

[Frank Knobbe <frank () knobbe us>]

On Sat, 2005-02-19 at 16:12 +0200, Willem Koenings wrote:
> - user input is correctly sanitized and there is no flaw
> - use input is not correctly sanitized and there is a flaw

I've seen cases where user input is correctly sanitized, but there was a
flaw.

If you tested your whole parameter set and don't find a flaw, it doesn't
mean that none exists. There could be a flaw that you haven't found with
your set of tests. That's what the quote is eluding to. You can say for
sure that there is a flaw, but you can not say for sure that there is
not one. You can't test for the absence.

> So above saying is not always completly true. But you can't use
> testing to find something you don't know at this exact moment -
> unknown flaws.

Well, that's exactly the point of the quote :)


Cheers,
Frank

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