Re: [WEB SECURITY] Universal XSS with PDF files: highly dangerous

[Amit Klein <aksecurity () gmail com>]

RSnake wrote:
> > The point is - someone with shared IP is vulnerable ONLY to an 
> > attacker with the same IP. Which makes attacks much less generic and 
> > much more painful. Rock solid it ain't, but I think it's a pretty 
> > good band-aid until all (hmmm...) clients upgrade to Acrobat Reader 8.0.
> >
> > -Amit
>
> Sorry for responding late, I've been doing some consulting work.
>
> After talking with some people on my blog I don't believe that is the
> case (at least not in theory).  Let's say Alice has an account with
> Bob's website.  Cathy is an attacker who owns a website that uses
> anti-DNS pinning.  
Of course anti-DNS pinning would work against my algorithm, but anti-DNS 
pinning is a larger problem, one that is out of scope here. I mean - so 
many things are broken when anti-DNS pinning is introduced... especially 
any IP-based security techniques. Anti-DNS pinning should be solved by 
browser vendors (if possible), regardless of the PDF problem. And at any 
rate, I feel that my algorithm makes the attack harder because it forces 
it to involve anti-DNS pinning.

Anyway, if you worry about the current anti-DNS pinning techniques, you 
may simply serve your PDF files in HTTPS only. I believe this will 
defeat the present day anti-DNS pinning techniques (in the sense that 
the user under anti-DNS pinning attack will get a certificate error 
before being served the PDF).

-Amit