Certificate Authority

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Denes, Laszlo

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Feb 25, 2020, 1:20:47 PM2/25/20
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Hello Everyone and thanks in advance for insights.

Never done this before hence the question as guidance.

We have a number of internal appliances now that complain that the site is not secure

I am assuming that this can be easily resolved through an internal Certificate Authority and can then be pushed to all users via computer GPO settings as seen below

https://docs.microsoft.com/en-us/windows-server/identity/ad-fs/deployment/distribute-certificates-to-client-computers-by-using-group-policy

 

But I have a few questions. We have 2 x 2016 DC and no other server that I can really put this on right now and would rather not bring up yet another server just for this, but I know it is not best practice to put it on a DC, but how risky is it?

Is it better to make your own certificate (internal only) or should I look at an external cert that I import and push out?

Can anyone make a suggestion for a clear article that explains the steps for this item?

Cheers in advance.

 

Laszlo Denes

Technical Analyst Servers

Information Systems

 

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Kurt Buff - GSEC, GCIH

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Feb 25, 2020, 3:17:48 PM2/25/20
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1) Are you going to have a single-tier CA? That's generally not a good idea.

2) Demoting or replacing the DC on which the Enterprise CA is installed will likely be problematic. See this article's answer:

3) I'm sure there are other reasons not to do this, and you should look at this article, and pay attention to the comments by, among others, Paul Adare and Brian Komar:

Kurt

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Denes, Laszlo

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Feb 26, 2020, 9:59:16 AM2/26/20
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Hey Kurt thank you… will look at it shortly…

 

Laszlo Denes

Technical Analyst Servers

Information Systems

Denes, Laszlo

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Feb 27, 2020, 8:38:31 AM2/27/20
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Okay I have found a 2016 server (WDS or WSUS) that I can install it on to avoid the DC issue. Thanks for pointing that out.

But other than that is there any better way to avoid the errors for users than installing a certificate and pushing it to desktops via GPO?

Would an internal one suffice or should I get an external Digicert, etc. ?

 

Laszlo Denes

Technical Analyst Servers

Information Systems

t: ext. 214

lde...@torontograce.org

 

From: ntsys...@googlegroups.com [mailto:ntsys...@googlegroups.com] On Behalf Of Kurt Buff - GSEC, GCIH
Sent: Tuesday, February 25, 2020 3:18 PM
To: ntsys...@googlegroups.com
Subject: Re: [ntsysadmin] Certificate Authority

 

1) Are you going to have a single-tier CA? That's generally not a good idea.

Dennis Pinckard

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Feb 27, 2020, 11:15:55 AM2/27/20
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Will the appliances EVER be accessible directly from an external PC?  Not through a VPN, but from somewhere on the internet?

If not, then don't pay for a certificate to put on them.

Is your internal DNS domain name the same as your external DNS domain name?  If not, then you probably won't be able to purchase a public certificate for them. Most public CAs will no longer issue certificates for internal domain names.  (company.ad, company.local)

An internal CA structure is generally fairly inexpensive, especially when compared to the cost of purchasing several external certs and renewing on a regular basis.


Another reason to NOT install a CA on a DC: DCs do not have local groups.  This makes it more difficult to lock down management of the CA.


Please install a 2-tier CA.  It will require 2 servers, but it gives so much more flexibility and security.

A very good reference that will walk you through step-by-step is from SANS: https://www.sans.org/reading-room/whitepapers/certificates/implementing-public-key-infrastructure-pki-microsoft-windows-server-2012-certificate-services-35427

It is written for 2012, but still applicable to a 2016/2019 server.  Just be sure to read completely through it before starting.  Once you have all of the information gathered, it generally should only take less than a day to get it set up.

I also recommend that you take the time to register for a Private Enterprise Number (PEN) as described in the document BEFORE you start.  It is not required, but can make things easier if you ever need to publish certificates publicly or federate with other companies.  It can take some time to get the PEN issued, but it is no cost and is perpetual.

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Kurt Buff - GSEC, GCIH

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Feb 27, 2020, 12:15:34 PM2/27/20
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I just read through the first half of that paper.

It's good, but they should have had a competent copy editor go through and correct a bunch of spelling, punctuation and usage errors.

Kurt

Michael Leone

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Feb 27, 2020, 1:19:44 PM2/27/20
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On Thu, Feb 27, 2020, 11:15 AM Dennis Pinckard <ntsys...@doomsdaypig.com> wrote:

I find that document very confusing, it's not really a step-by-step HOWTO, IMO. I got lost reading it, even on things I know how to do, and have already done. :)

Denes, Laszlo

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Feb 27, 2020, 1:49:06 PM2/27/20
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Thank you for the detailed insight J

No they will never hit the Internet.

 

Laszlo Denes

Technical Analyst Servers

Information Systems

t: ext. 214

lde...@torontograce.org

 

Dennis Pinckard

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Feb 27, 2020, 8:41:36 PM2/27/20
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I agree.  I used it as a primary reference for the last 3 companies to build PKI.  The configs and scripts were used as a basis for my own PowerShell scripts to automate most of the setup.

There are other sources from the web that I also use, as well as "the book" from Microsoft (Really wish they would update that).  I like the SANS document for the explanations in the 1st half.  Most of the other walk-throughs I've seen just do step-by-steps, but I didn't feel they explained enough of what the options are or how they interact.

Currently, my team is expanding our 2-tier to add a 2nd Issuing CA.  The original will be used for user/workstation certs with the new CA handling server/applications.  I can foresee eventually adding a third to handle the non-windows appliances.  Mostly the reason is to split the management roles among different groups. 

Additionally, I am walking my team through building a two-tier PKI in our test domain.  It is really appreciated since it is not a system that gets built very often and most of the team don't really have much knowledge of how it all works.

Dennis Pinckard

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Feb 27, 2020, 9:01:28 PM2/27/20
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The 1st half covers some of the concepts and the 2nd half covers the installation and configuration.

Here are some other sources you can refer to:

https://777notes.wordpress.com/2016/07/11/certificates-the-dos-and-donts-of-pki/

https://www.derekseaman.com/2014/01/windows-server-2012-r2-two-tier-pki-ca-pt-1.html

https://social.technet.microsoft.com/wiki/contents/articles/15037.ad-cs-step-by-step-guide-two-tier-pki-hierarchy-deployment.aspx

https://timothygruber.com/pki/deploy-a-pki-on-windows-server-2016-part-1/

https://blogs.technet.microsoft.com/xdot509/tag/operating-a-pki/

https://blogs.technet.microsoft.com/pki/2010/04/20/disaster-recovery-procedures-for-active-directory-certificate-services-adcs/

https://social.technet.microsoft.com/wiki/contents/articles/10942.ad-cs-security-guidance.aspx

It's been a while since I went through my Certificate Services links folder.  Too many of them are broken now.  The ones above were working just now.

The best advice I can give is to read up on AD CS and try to plan out the design before you get started. 

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Denes, Laszlo

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Feb 28, 2020, 10:42:30 AM2/28/20
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Thanks for all the great insights and discussion

 

Laszlo Denes

Technical Analyst Servers

Information Systems

t: ext. 214

lde...@torontograce.org

 

From: ntsys...@googlegroups.com [mailto:ntsys...@googlegroups.com] On Behalf Of Dennis Pinckard
Sent: Thursday, February 27, 2020 9:01 PM
To: ntsys...@googlegroups.com
Subject: Re: [ntsysadmin] Certificate Authority

 

The 1st half covers some of the concepts and the 2nd half covers the installation and configuration.

Michael Leone

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Feb 28, 2020, 11:02:36 AM2/28/20
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On Thu, Feb 27, 2020 at 9:01 PM Dennis Pinckard <ntsys...@doomsdaypig.com> wrote:

The 1st half covers some of the concepts and the 2nd half covers the installation and configuration.

Here are some other sources you can refer to:


This one's broke, BTW, came up 404 Unknown page.

Michael B. Smith

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Feb 28, 2020, 11:27:05 AM2/28/20
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Interesting.

 

It’s still in the cache. I referred to it just a couple weeks ago.

 

https://cc.bingj.com/cache.aspx?q=blog+operating+a+pki&d=4683322669210170&mkt=en-US&setlang=en-US&w=_W9t2Tqn9PtRuoq6V8qrpXI-QLsXX-FH

 

From: ntsys...@googlegroups.com [mailto:ntsys...@googlegroups.com] On Behalf Of Michael Leone
Sent: Friday, February 28, 2020 10:02 AM
To: NTSysAdmin
Subject: Re: [ntsysadmin] Certificate Authority

 

On Thu, Feb 27, 2020 at 9:01 PM Dennis Pinckard <ntsys...@doomsdaypig.com> wrote:

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Michael Leone

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Feb 28, 2020, 11:30:47 AM2/28/20
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On Fri, Feb 28, 2020 at 11:27 AM Michael B. Smith <mic...@smithcons.com> wrote:

Interesting.

 

It’s still in the cache. I referred to it just a couple weeks ago.

 

https://cc.bingj.com/cache.aspx?q=blog+operating+a+pki&d=4683322669210170&mkt=en-US&setlang=en-US&w=_W9t2Tqn9PtRuoq6V8qrpXI-QLsXX-FH


It's been archived, since it's an article from 2013, apparently. I searched the blog site., Note the different URL ...


 

 

From: ntsys...@googlegroups.com [mailto:ntsys...@googlegroups.com] On Behalf Of Michael Leone
Sent: Friday, February 28, 2020 10:02 AM
To: NTSysAdmin
Subject: Re: [ntsysadmin] Certificate Authority

 

On Thu, Feb 27, 2020 at 9:01 PM Dennis Pinckard <ntsys...@doomsdaypig.com> wrote:

The 1st half covers some of the concepts and the 2nd half covers the installation and configuration.

Here are some other sources you can refer to:

https://blogs.technet.microsoft.com/xdot509/tag/operating-a-pki/

 

This one's broke, BTW, came up 404 Unknown page.

 

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