Re: Checkpoint smart defance as IPS

[Shreyas Zare <shreyas () secfence com>]

Hi Craig,

I disagree with you my friend. And the points you are using to defend
your previous claim are totally different and thus not valid for the
argument.

Firstly, you claim that SSL/TLS can be intercepted and MITM is
possible (and effectively protocol is broken). And now you defend it
citing bad implementation of SSL/TLS in browsers and social
engineering. Most of your points (like phishing, fake domains etc) are
social engineering and not MITM or interception for that matter.

SSL/TLS is not to protect user from his/her stupidity. SSL/TLS do
provide a secure channel to a site and you cannot just sniff the
traffic and decrypt it (as you suggest).

DNSSEC is not related to SSL/TLS security. Clients just blindly trust
their ISP DNS server. DNSSEC is to make faking/spoofing a DNS reply
really difficult and it will be done using digital signatures. And
surely, you can attack DNSSEC too with social engineering or making
the client machine trust a fake CA that you control then sign a fake
reply with your private key.

Again I would say my point: you *cannot* do MITM on a website if you
don't have private key for the certificate on that website. However,
you can be a CA and fake a certificate on the fly on your gateway,
that too only when the client trusts the CA in the first place. If you
are NSA, you can crack the encryption with brute force and that too
will take quite some time.

And ...

On Thu, Jun 3, 2010 at 4:45 AM, Craig S. Wright
<craig.wright () information-defense com> wrote:
> Hello,
> I suggest that you learn to reference more than simply Wiki.

I suggested you wiki to get the basics. and wikipedia for that matter
is really good. You claimed that browser only checks for domain name
and totally didn't know about the handshake which involves private key
of the website.



> "If it was possible as you claimed, the protocol will be totally broken and
> it will be front page news article."
> I suggest you keep up. This is why TLS was introduced (which also has flaws)
> - which is still not used correctly either. But read on for something that
> matters.
> http://blog.washingtonpost.com/securityfix/2006/02/the_new_face_of_phishing_
> 1.html

Phishing is not MITM, its social engineering.



> PS. A complete compromise of the CAs and DNS would not likely make a front
> page article. Most people do not care and it is not something that sells
> papers.

A persons net-banking account can be intercepted while he and his bank
wont care? great!



> This is also why DNS and routing are important. What do you think DNSSEC is
> really about?

DNSSEC and SSL/TLS are different things. SSL/TLS use certificates to
match domain that's true but, the handshake is done as client sends a
random number encrypted with public key and the server which has the
private key can *only* decrypt it.




> SSL is about privacy, NOT security. It was NEVER about security.

this is simply great!




> How about I give you some real reading, something more than the online
> golden book encyclopaedia that is Wikipedia...

Thanks, I have done much more reading already.




> Let's take a quote from Kurt Seifried:
> "Even ignoring all these problems the simple fact is that SSL certificates
> only identify the server to the user, they do not authenticate it. This is a
> subtle but incredibly important difference. My online bank is at tdbank.ca,
> td.ca on the other hand is owned by someone else and banktd.ca is still
> free. I know for example that www.openssl.org is the "official" site for
> OpenSSL, but what about www.openssl.de? Shouldn't that be the official site
> for OpenSSL translated into German? Well it turns out that it isn't. Do you
> trust every single root certificate in your webbrowser software? Have you
> even heard of "IPS SERVIDORES" (ips.es), "Saunalahden Serveri CA"
> (saunalahti.fi) or "SERVICIOS DE CERTIFICACION - A.N.C." (correo.com.uy)? I
> sure as heck haven't."
>
> REMEMBER - ALL CERTIFICATE AUTHORITIES ARE EQUALLY TRUSTED!!!!!!!!!!!!!!!!
>
> I have to state this again...
>
> ALL CERTIFICATE AUTHORITIES ARE EQUALLY TRUSTED!!!!!!!!!!!!!!!!
>
> Do you think your users go and check the CA and ensure it is really the one
> that the real site has used? If you think users do this, you have some
> learning to do.
>
> If you actually believe that you cannot obtain a signed (from a CA in IE's
> list) certificate for a MiTM device, you have not looked too hard.
>
> If you do not think this is a known issue, try reading some RFC's:
> "[Browser vendors] and users must be careful when deciding which certificate
> and certificate authorities are acceptable; a dishonest certificate
> authority can do tremendous damage."
> RFC 2246, The TLS Protocol 1.0
>
> The 264+ root CAs trusted by Microsoft, the 166 root CAs trusted by Apple,
> and the 144 root CAs trusted by Firefox are capable of issuing certificates
> for any website, in any country or top level domain.
> See Ed Felten. "Web Certification Fail: Bad Assumptions Lead to Bad
> Technology". Freedom To Tinker, February 23 2010.
> www.freedom-to-tinker.com/blog/felten/web-certification-fail-bad-assumptions
> -lead-bad-technology.


Again for god sake, this is social engineering! there is no way this
can be used to MITM an existing SSL website. Well, if you can get a
cert from any of the 264+ CA for citibank, that would be fault of the
CA and not SSL/TLS or PKI, plus that would involve legalities. This
compromise is in theory possible, but again you need access to a CA
and SSL/TLS protocol is still not broken (its working as designed)




> Next, "'Packet Forensics' devices are designed to be inserted-into and
> removed-from busy networks without causing any noticeable interruption [. .
> . ] This allows you to conditionally intercept web, e-mail, VoIP and other
> traffic at-will, even while it remains protected inside an encrypted tunnel
> on the wire. Using `man-in-the-middle' to intercept TLS or SSL is
> essentially an attack against the underlying Diffie-Hellman cryptographic
> key agreement protocol [. . . ]".
> Packet Forensics. Export and Re-Export Requirements, 2009.
> www.packetforensics.com/export.safe.
>
> So - the question is... have you removed all but the "trusted" CA's from
> your users browsers? I doubt it. If you have, you also need to do this EACH
> and EVERY time that IE updates.

Again you need access to a CA, which a government like US can do for
sure. And its again not possible for any guy to obtain the same.




> Next, have a read of more than this forum. Try the TLS list from the IETF:
> http://www.ietf.org/mail-archive/web/tls/current/msg03928.html

> From the link:
"The problem:  when Microsoft IIS is configured to request a client
certificate after having received the request, then it WILL perform
an unauthenticated request!  Sending the reply back only to the
authenticated client is a poor excuse for acting on an unauthenticated
request."

That is bad implementation of SSL, isn't it? and that too specific to
a particular server. And in normal HTTPS scenario, client don't send a
cert to server.




> Even not paying for a certificate (which is the option for the scenario this
> derived from), you can still attack SSL/TLS:
> "...inject a chosen plaintext prefix into the encrypted data stream, often
> without detection by either end of the connection. This is possible because
> an "authentication gap" exists during the renegotiation process at which the
> MitM may splice together disparate TLS connections in a completely
> standards-compliant way."
> See
> http://extendedsubset.com/wp-uploads/2009/11/renegotiating_tls_20091104_pub.
> zip
>
> Finally, have you ever thought of a zero bit negotiated key. SSL with 0-bit
> encryption. This can be done using a 128 bit certificate. The client to the
> IPS is clear text, but looks to the browser as being encrypted.


Again an example of bad implementation in application.




> Research means more than wiki. If you use a title of researcher, it is
> something that you should try to do.

Thanks for the tip. But, one really needs to read basics first not
matter from wiki or some another source.



> Regards,
> ...
> Dr. Craig S Wright GSE-Malware, GSE-Compliance, LLM, & ...
> Information Defense Pty Ltd



Lastly, why on earth would people use electronic banking if what you
claim is true and so easy to carry out? While there are many attacks
possible in theory, implementing them practically is very difficult
indeed. And such attack will depend on bad implementation issues or
social engineering. Still, doing a attack based on social engineering
is quite viable option but, the success rate of such attack would vary
with the target population.


Regards,

Shreyas Zare

Sr. Information Security Researcher
Secfence Technologies
www.secfence.com

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