More accurately, it will warn the user if their *browser* doesn't
trust the CA. SSL solutions like Bluecoat are used pretty widely to
allow network administrators/security groups/compliance groups
visibility into that traffic. Typically where SSL is being
intercepted and re-signed by the appliance, a GPO push is down of the
new CA to ensure users aren't constantly getting certificate warnings.
On the policy side of things, clearly users need to be advised of the
company policy and sign off on it - which should be true for all
monitoring regardless of whether it's encrypted or not.
As a side note, once you've decrypted the SSL like this it's pretty
trivial to check the type of traffic and deny someone who's trying to
tunnel ;)
Cheers,
---
Tremaine Lea
Network Security Consultant
Intrepid ACL
"Paranoia for hire"
On 11-Dec-07, at 10:28 AM, Scalcione.David wrote:
is there any standard mechanism (in SSL standard or in HTTP standard)
to send actual CA certificate to the browser by forward proxies?
I think that would defeat the whole purpose of SSL. The whole point
of SSL is to warn the user if they don't trust the CA. Users would
need to manually install that CA cert before that kind of IPS system
would work. Otherwise they'd get a security warning every time they
access an SSL connection. If it WERE possible to make the browser
display a prompt to install the CA cert, the IPS device would not
know if the user ever installed it and would prompt them to install
it every time they opened an SSL connection. Also, remember, any
protocol can travel through SSL. It's not always a browser as the
SSL client, could be email, VPN, etc.
Dave
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
] On
Behalf Of Ravi Chunduru
Sent: 08 December 2007 18:33
To: [email protected]
Subject: SSL - Man-in-the-Middle filtering
it seems that some network IPS devices and application firewalls are
not only providing SSL based HTTP inspection on server side, but also
on client side (i know of one IPS device which is in beta testing).
i understand that it is required as attacks can be sent in SSL to
avoid blocking.
when deployed on client side, these devices resign certificates (of
public servers) with local CA certificate. i see two aspects to it -
users need to trust local authority (enterprise administrators) and
second is users will have false sense of security (that is users are
no longer see the actual CA of server certificate).
any comments on acceptance of this functionality in enterprise
deployments?
is there any standard mechanism (in SSL standard or in HTTP standard)
to send actual CA certificate to the browser by forward proxies?
thanks
Ravi
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