From: Simon Spero <ses@tipper.oit.unc.edu>
Date: Fri, 13 Oct 95 12:50:45 PDT
To: cypherpunks@toad.com
Subject: Same ol' massive MITM exposure in Netscape 2.01b
Message-ID: <Pine.SOL.3.91.951013122654.26464D-100000@chivalry>
MIME-Version: 1.0
Content-Type: text/plain



Just to repeat old news: Netscape 2 has similar  exposure to MITM attacks 
to 1.1. 

Netscape 2 does make one variant of the MITM attack less useful: The 
new document  info page allows information to be obtained about inlined 
images as well as the base page; this breaks the old attack of only 
intercepting inline image requests (which can be used to steal 
information in request headers without there being any chance of your 
certificate showing up). 


1) The client does not do any verification that the certificate used for 
the transaction is one associated with the server, allowing MITM 
substitutions as long as the server has a properly signed certificate

2) The client does not issue warnings for redirections from one https 
page to another https page, even if the url to which it is redirected has 
a different hostname to the url originally dereferenced.

3) In the case of redirection, the document info screen does not provide 
information about the originaly referenced page, just the final page. 
This allows the MITM to intercept the first request, steal the request 
data, then issue a redirect to hide the certificate used in the intercept. 

4) In the beta version, the document info page does not display the 
security info (I did check with  MITM disabled). 


Simon

-----
(defun modexpt (x y n)  "computes (x^y) mod n"
  (cond ((= y 0) 1) 	((= y 1) (mod x n))
	((evenp y) (mod (expt (modexpt x (/ y 2) n) 2) n))
	(t (mod (* x (modexpt x (1- y) n)) n))))