Solved

Revoked Certificates still valid for authentication

Posted on 2013-06-17
6
1,137 Views
Last Modified: 2014-06-11
Hi,

I have recently installed a new standalone root Microsoft Certificate Authority and a subordinate Enterprise CA into our Active directory environment.

The Standalone Root is kept powered off and will remain so, and the Sub is issuing day to day certificates.
The problem I am seeing is that I have issued a certificate to myself a certificate using the Default 'User' Template and then transferred that to my iPhone to use for authentication with Microsoft Exchange.
It works! I get the email even when my password has been changed.

My problem comes when I try to revoke a certificate on the Sub CA.

When viewing the Certificate on my Windows 7 Machine the certificate path still says 'This Certificate is OK.'


When I run cerutil -f -urlfetch -verify MyCertificate.cer

The final result is
'Certificate is REVOKED'
Leaf certificate is REVOKED <Reason=6>
CertUtil: -verify command completed successfully.



So manually checking the status shows it has been revoked. But my iPhone is still fetching and sending email. And the Certificate path on my Windows 7 Machine still says 'OK'


Is there anything I Might of missed?
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Question by:Badger1879
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6 Comments
 
LVL 11

Expert Comment

by:Dmitriy Ilyin
ID: 39252966
try to run
certutil -urlcache * delete
and then check again
0
 
LVL 16

Expert Comment

by:Bruno PACI
ID: 39253093
Hi,

Certificate Revocation List are published through http.
If you take a look at your certificate properties on your computer you should find a CRL distribution points  list of URLs that should point to a URL that hosts revocation lists.
When your computer has to use a certificate it is supposed to try to reach the CRL distributon point to check for the revocation.
If it can't reach the CRL the computer just consider that certificate is not revoked.


When you revoke a certificate on the CA, th CA is supposed to update the CRL distribution point but this distribution point may not be configured nor installed...

About iPhone, if the device is connected externally to Internet, then the CRL list won't be reachable from outside if you did not published it !! So, no chance for the iPhone to know about any certificate revocation if you did not published your CRL distribution point to the Internet !!

Have a good day.
0
 

Author Comment

by:Badger1879
ID: 39253209
Thank you for your help,

dlSmlSS where am I supposed to the command?

I have ran it on a few of our domain controllers and some do not have the new CRL in there cache.

I have also ran the command on my Windows 7 machine and now running certutil -urlcache comes back saying failed as there is no more data.

PaciB,

I don't fully understand; I thought that the check would be done internally.. for example the internal Exchange server would check the Certificates validity when the iPhone tries to connect.
I didn't think that the iPhone checked whether it was valid.. I always thought that is what the server is for.

Also the iPhone was on the Corporate network when I was testing this so it should of been able to see the CRL Distribution point on the HTTP point.

Any more ideas?
0
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LVL 11

Expert Comment

by:Dmitriy Ilyin
ID: 39253220
same machine that u ran
cerutil -f -urlfetch -verify MyCertificate.cer
did u try to open certificate after this commend and check its status?
0
 
LVL 16

Accepted Solution

by:
Bruno PACI earned 500 total points
ID: 39253235
Sorry,

Client certificates are checked by the server, server certificate is checked by the clients.

So you should ensure that your internal servers are able to reach your CRL distribution point internally.

About external clients reaching ActiveSync through TMG or ISA, it is the TMg (ISA) server that needs to check the client certificate revocation.
You should then ensure that your TMG/ISA server is able to reach the CRL distribution point (DNS resolution of the distribution point URL + IP routing available to this IP + IP traffic allowed to this IP).
0
 

Author Comment

by:Badger1879
ID: 39377467
Ok.. It has been a while since I have updated this but I have been checking and checking...

The revokation checking is working if I manually export the certificate and run

certutil -f –urlfetch -verify certfile.cer

This shows that the certificate is Revoked.


Also opening MMC and viewing Enterprise PKI shows that all CDP, AIA and CA Certificate are valid locations on the root and the sub server.

I cannot see what the problem is!

Manually checking is showing that the certificate is revoked! why is AD, PCs and the exchange server showing that this is an ok certificate!!


Anyone? I really need help
0

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