How much can we trust Certificate Authorities in issuing and securing certificates?

Question

This is a general question not related to any particular website or a CA (Certification Authority).

We all know that HTTPS is an encrypted protocol, but one that relies on CAs issuing digital certificates to websites with due regard. Now, its theoretically possible for a CA to issue a proper certificate to a malware hosting site, is it not? In other words, CAs are the weakest link in the security chain of HTTPS. If that happens, then what are the implications?

Additionally, we also know that the data we browse on the internet passes through multiple hops and nodes (your ISP, the website's ISP, caches and proxies like CloudFlare, etc). Suppose if any of these entities in between got hold of the website CA certificate (public and private keys), can they capture the data being transferred? If yes, then what is a good alternative to the present HTTPS system?

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There is another aspect of concern with HTTPS, though it may not be related to any CAs. Nowadays, every now and then you get laptops and other gadgets that come pre-installed with dicey browser certificates that allows a phishing site to be opened without any regard (Dell and Lenovo models had such cases recently, I don't have any links but you can Google them). Again, this can also be deemed as a weakness of the HTTPS system.

Answer 1

I'm not saying that CAs aren't doing their job well, but its theoretically possible for a CA to issue a proper certificate to a malware hosting site, is it not?

CAs are NOT responsible for policing the content of sites they are issuing certificates to. It's simply not part of their job description. Their responsibility is to make sure they only issue certificates to a domain name's legitimate owner, and if that owner decides to host malware, so be it.

Thus, you should not rely on the existence of HTTPS on a site as an indicator of legitimacy. The only potential exceptions to this are sites with extended validation certificates (indicated by the company name showing in the address bar). CAs must verify that the organization is legally recognized and has a physical presence before issuing such certificates, so these sites are much more likely to be legitimate. Nonetheless, it is still possible for them to host malware, either intentionally or accidentally.

Additionally, we also know that the data we browse on the internet passes through multiple hops and nodes (your ISP on the cloud, the website ISP, caches and proxies like CloudFlare, etc). Suppose if any of these entities in between got hold of the website CA certificate (public and private keys), can they capture the data being transferred? If yes, then what is a good alternative to the present HTTPS system?

If the private key is leaked, then indeed it would be possible for anyone possessing the private key to read the data. Ideally, the website owner would keep the private key on his/her own webserver so that it is not possible for ISPs or any other entity to obtain it. If the website owner decides to keep the key in the hands of a hosting provider, cloud server provider, proxy provider, etc, then the website owner implies that he/she trusts those providers with access to the data.

Answer 2

possible for a CA to issue a proper certificate to a malware hosting site

HTTPS cares only about the securing the transport. It does not make any statements about the server or the transferred data. I.E. it is possible to use HTTPS to transfer malware or to transfer sensitive information which then get compromised because the server got hacked.

passes through multiple hops ... got hold of the website CA certificate

If someone in the middle gets hold of the certificate's private key a perfect and undetectable man in the middle attack can be done. That's why the key is called "private" or "secret".

then what is a good alternative to the present HTTPS system?

There are no current alternatives which have at least the security of HTTPS and don't rely on private/secret data. If these data gets compromised (which you assume can be done) man in the middle is possible, like with normal HTTPS.