Since MD ICAP Server is using native secure channel of Windows for TLS (Schannel) to communicate with MD Core, the behavior of revocation is managed by Windows OS: the certificate revocation server needs to be accessible for the account running ICAP.
Thus, if the revocation server is not available, you might encounter: “The revocation function was unable to check revocation because the revocation server was offline.”
Solution
Please verify certificate revocation list availability and validity, and test certificate revocation.
Example: after you export your leaf certificate into leafCertificate.cer
Run the following commands:
certutil -urlfetch -verify leafCertificate.cer certutil -user -urlfetch -verify leafCertificate.cer certutil -url leafCertificate.cerTo check certificate revocation under SYSTEM and Network Service context, run the same commands as below. Requires: PSTools
psexec -s certutil -urlfetch -verify c:/temp/leafCertificate.cer psexec -u "nt authority\networkservice" certutil -urlfetch -verify c:/temp/leafCertificate.cer psexec -i -d -u "nt authority\networkservice" certutil -url c:\temp\leafCertificate.cerAlternatively, you can add the following in MD ICAP Server’s configuration, to disable SSL certificate check on ICAP’s side: create and set “verifypeer” to “false” in “internal” section of configuration. Then restart the service.
Note: this setting causes potential security risk, so it is not recommended.
Windows: HKEY_LOCAL_ MACHINE\SOFTWARE\OPSWAT\ICAP Server

Linux: mdicapsrv.conf

For further assistance regarding Unable to Check Revocation for the Certificate, please follow these instructions on How To Create a Support Package, before creating a support case or chatting with our support engineer.
