GRC has created HTTPS/SSL Fingerprints. This service allows you to check whether or not your enterprise is performing MITM on the SSL secured site that you are trying to reach. It compares the certificate fingerprint to what you would receive to the fingerprint that they receive by going direct. If they are the same, the certificate is authentic and you have no problem. If they are different, then it is likely that someone is performing MITM on your SSL connection.