At https://www.auskec.kr/ (in Opera, on Windows) I get
~~~~~
Web Protection by
Bitdefender
Suspicious page blocked for your protection
https://www.auskec.kr/
Your connection to this web page is not safe due to an untrusted security certificate.
Phishing sites often use fake certificates that trigger this alert, and their goal is to obtain your sensitive information.
TAKE ME BACK TO SAFETY
I understand the risks, take me there anyway
If you know this page is not dangerous, you can add it to your Exceptions list of trusted websites. Be aware that you will not be warned about any threats existing on this page.
~~~~~
However, based on my basic knowledge of certificate problems, it doesn't seem to be an issue of the certificate being missing, nor with wrong dates, nor with wrong URL/domain. In fact, the certificate even seems to be issued by BitDefender. Or maybe the data are in the wrong fields; e.g. "www.auskec.kr" is stored in "Certificate Subject Alternative Name". Or maybe just something else wrong/missing.
If I ignore the BD warning, then Opera says the "connection is secure" and the "certificate is valid". Although there's still some problem, as I don't see any content. (The site content comes up OK through regular HTTP though.)
Why is that so?