CRL Checking and risks with disabling it

[glen8]

Hi Everyone,

We are managing clients on the LAN, DMZ (Domain joined and workgroup) and Internet.  Currently everything is running over SSL and we have only enabled the correct ports for SCCM between our DMZ and LAN.

There is one niggle though.  Currently there is only one root CA server with no subordinates.  Obviously this server is not accessible from outside of the LAN.  Due to this, CRL checking has been disabled for clients and 443 IIS management sites on both the primary sccm server and an additional site server living in the DMZ.

Microsoft say this on their website:

"The requirement to check the CRL for each connection to a site system configured to use a PKI certificate is larger than the requirement for faster connections and efficient processing on the client, and is also larger than the risk of clients failing to connect to servers if they cannot locate the CRL."

I'm not sure I completely agree.  Due to last years huge virus outbreaks across the world, and the UKs NHS shutting down due to malware I would say the risk in not knowing if all your clients are healthy now outweighs any security risk in disabling CRL.

at some point no doubt we will redesign our certificate servers but not for a while.

Thoughts?

[GarthMJ]

Two questions.

• Why not create a CLR that is accessible from the internet?
• Why use HTTPS at all if you are not going to use one of its main features. 

[glen8]

If I modified our root CA to include a new CRL DP pointing to the SCCM server already living in the DMZ, what ports do I need to open between the certificate server (LAN) to the DMZ?

This is something the network team don't like doing though (opening ports I mean)

also, how do I quickly and easily get all clients to renew their certificates?

[glen8]

Duplicated post

[GarthMJ]

You can have more than one CRL, so you could set it up with no extra ports needed. 

[glen8]

22 minutes ago, GarthMJ said:

You can have more than one CRL, so you could set it up with no extra ports needed. 

How would the certificate server (lan) update the crl point (dmz)

[GarthMJ]

it will depend on which CRL method but you should be able to copy the file from one to the other. 

[glen8]

ok, ill open port 445 and watch on the firewall for traffic

 

thanks for your help