Re: Obfuscated web pages

I beg to differ on that comment.

I believe that what would be foolish is to suggest that it is 
theoretically possible to do effective (let alone efficient) inline JS 
inspection and alerting/blocking, unless of course that suggestion comes 
along with the theoretical support for such a theoretical hypothesis.

In absence of that we are just left with an escalating arms race of 
practical implementations of obfuscation techniques vs. 
de-obfucation+dynamic analysis techniques.

My impression is that in such a scenario the odds are heavily biased 
against the defensive network device. My admittedly simplistic rationale 
for such a far fetched thought is that all the principles applicable to a 
L-4 network IDS outlined by Ptacek & Newsham 10 years ago also apply to 
this problem and are compounded by the fact that maintaining and 
monitoring state of a DOM parser and a JavaScript engine is much more 
difficult than doing it for an endpoint's TCP/IP stack.

My hunch is that the best way to do this is directly at the endpoint and 
not just anywhere at the endpoint but within the browser and right in the 
JS engine

-ivan


Mike Barkett wrote:
> Regarding inline JS inspection, I've said it before and I still believe that
> one day there will be a full DOM proxy product that is capable of running
> inline.  Yes, its speeds will lag other network devices, and yes, browser
> attacks will probably be yesterday's news by then anyway, but it would be
> foolish to suggest that it is theoretically impossible to do.  In the
> meantime, if you have embraced defense-in-depth and gotten yourself a
> trustworthy network IPS, a thorough endpoint solution, and you use only
> locked down browsers, then you'll be ok.
> 
> -MAB
> 
> 

-- 
"Buy the ticket, take the ride" -HST

Ivan Arce
CTO

CORE SECURITY TECHNOLOGIES
http://www.coresecurity.com

PGP Fingerprint: C7A8 ED85 8D7B 9ADC 6836  B25D 207B E78E 2AD1 F65A


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