Re: [Full-disclosure] Apple Safari ... DoS Vulnerability

[Nick FitzGerald <nick@xxxxxxxxxxxxxxxxxxx>]

Michal Zalewski to me:

> > But what if www.evil.com has run an injection attack of some kind (SQL,
> > XSS in blog comments, etc, etc) against www.stupid.com?
> >
> > Visitors to stupid.com then suffer a DoS...
> 
> In such a case, the attacker may just as well clobber body.innerHTML,
> run a while (1) loop, or otherwise logically deny or alter service to
> visitors without actually exploiting any specific bug ...

So?

> ... - so I do not
> see any significant benefit to killing this particular tab.

Where in any usable definition of "denial of service" does the word 
"useful" or concept of "benefit" appear?

The question was, is it a DoS.

It is.

> Crashing / hanging the entire browser is somewhat different, as it
> bears some risk of data loss in plausible usage scenarios.
> Unfortunately, most implementations do very little to prevent cases
> that were permitted by standards in the first place (things such as
> "while (1) str += str", "while (1) alert('foo')", looped blocking
> XMLHttpRequest calls, ridiculously nested XML and other
> expensive-to-render content, etc) - which makes finding new instances
> somewhat futile and pointless, and a result, somewhat frowned upon on
> security mailing lists (ugh).

I agree, but I was not addressing that.

Is it useful?  Probably not.

But it's still a DoS...

And, will the Safari folk find something more important to fix if/when 
they look into it?

Who knows but it won't hurt for them to look...


Regards,

Nick FitzGerald


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