Re: SSL - Man-in-the-Middle filtering

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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