Re: Apple Safari ... DoS Vulnerability

[Nick FitzGerald <nick () virus-l demon co uk>]

Chris Evans to me:

> By this definition of yours, DoS is fundamentally built in to browsers
> (by way of simply following specifications) -- even those with decent
> privsep models.

Not necessarily...

Factually, probably so but that says more about our s/w development 
methods and what has (historically) passed as "acceptable" in that arena.

Browsers could reasonably implement various kinds of resource expenditure 
limitations, but few, if any, do OOTB (FF 2.x I think added some basic 
"this script is taking too long" controls, but there is a lot more that 
could be done).

Is that specification antagonistic?  Arguably yes because the 
specifications don't say "... to N levels of recursion" and such.

But maybe that tells us an awful lot about the specifications and the 
culture of the folk who wrote them?

Yep -- they came from that "she'll be right" s/w dev background that is 
responsible for most of the crap that means we're assured of jobs for 
life (well, if you're as old as me anyway!).

> Web security IS fundamentally broken at the foundations, so I'm not
> going to disagree with you.

8-)

> It raises the question: DoS is an overloaded term, ...

DoS is not an overloaded term -- it means pretty much what it says, as 
Thierry pointed out.

Yes, a lot of noobs and journalists confuse it with _D_DoS and its usual, 
deliberate "with malicious intent" connotation, but that might just be an 
education problem...

> ... perhaps it should
> be reserved for cases that actually have real-world significance? Or
> is a new term required?

How do we operationally define "real-world significance"?

That was my original point -- this is a DoS

Whether it's "worthy" of discussion here or not is a different issue that 
touches precisely on the issue of defining "real-world significance".

There may be some subtle use for such a vuln that allows it to be 
combined with one or more other "minor" vulns to make for a modestly 
worrying attack, or there may not.  Until that is found (probably by a 
Black Hat because White Hats are so quick to dismiss things like this 
with "it's only a trivial browser tab-closing DoS" and move on to sexier 
sounding bugs) this may be ignored because no-one deems it "worthy", 
extending the long, sad history of quality neglect in s/w development.


Regards,

Nick FitzGerald


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