Re: [fw-wiz] Firewall best practices



On Tue, Apr 27, 2010 at 11:12:40AM -0500, Fetch, Brandon wrote:
Too late:
http://files.cloudprivacy.net/ssl-mitm.pdf

And these devices are already in deployment...now, imagine one of these with a wildcard certificate running at a coffee house, or at the aggregation point within a provider's CO POP...

Where it would generate cert errors for every user?

These only make sense where you can install the proxy's wildcard cert on all of
the client machines. Neither coffee houes, nor ISPs can do this.

-----Original Message-----
From: firewall-wizards-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:firewall-wizards-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of John Morrison
Sent: Tuesday, April 27, 2010 5:45 AM
To: Firewall Wizards Security Mailing List
Cc: mjr@xxxxxxxxx; Firewall Wizards Security Mailing List
Subject: Re: [fw-wiz] Firewall best practices

My understanding of https (and other PKI-based encryption) is that
only the holder of the private key can decrypt the data encrypted with
the other (public) key in the pair. My view is that the firewall can
only decrypt and inspect https traffic if it is acting as the server
to the external client. It can't intercept and decrypt https traffic
destined for another device - the real server. If it did https would
be worthless. Any hacker could buy such a firewall to sniff and
decrypt all https traffic.

On 23 April 2010 20:18, <david@xxxxxxx> wrote:
On Fri, 23 Apr 2010, Martin Barry wrote:

$quoted_author = "Marcus J. Ranum" ;

That's why firewalls need to go back to doing what they
originally did, and parsing/analyzying the traffic that
flows through them, rather than "stateful packet
inspection" (which, as far as I can tell, means that
there's a state-table entry saying "I saw SYN!")

Marcus, are you referring to DPI or proxies or both or something else
entirely?


If the firewall doesn't understand the data it's passing,
it's not a firewall, it's a hub.

If an application emulates HTTPS traffic and is proxy aware, how do you
tell
the difference?

There are firewalls on the market that can decrypt HTTPS traffic (and I
believe be configured to block any traffic that they can't decrypt)

David Lang
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Relevant Pages

  • Re: [fw-wiz] Firewall best practices
    ... To quote a presenter at a security course I attended "If the user is ... only the holder of the private key can decrypt the data encrypted with ... only decrypt and inspect https traffic if it is acting as the server ... destined for another device - the real server. ...
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  • Re: [fw-wiz] Firewall best practices
    ... My understanding of https (and other PKI-based encryption) is that ... only the holder of the private key can decrypt the data encrypted with ... only decrypt and inspect https traffic if it is acting as the server ... destined for another device - the real server. ...
    (Firewall-Wizards)
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    ... It boils down to included "already trusted CA's" on the browser and a complicit CA cooperating with a nefarious entity to issue another cert for a targeted domain. ... The hardware device the paper refers to can have this cert installed and proceed to impersonate the targeted domain thus decrypting all traffic destined for that destination. ... only decrypt and inspect https traffic if it is acting as the server ... destined for another device - the real server. ...
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  • Re: [fw-wiz] Firewall best practices
    ... My understanding of https (and other PKI-based encryption) is that ... only the holder of the private key can decrypt the data encrypted with ... only decrypt and inspect https traffic if it is acting as the server ... destined for another device - the real server. ...
    (Firewall-Wizards)