Why do browsers show ugly errors for untrusted SSL certificates?

Question

When faced by an untrusted certificate, every single browser I know displays a blaring error like this:

Why is that?

This strongly discourages web developers to use an awesome technology like SSL out of fears that users will find the website extremely shady. Ilegitimate (ie: phishing) sites do fine on HTTP, so that can't be a concern.

Why do they make it look like such a big deal? Isn't having SSL even if untrusted better than not having it at all?

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It looks like I am being misunderstood. I am taking issue with the fact that HTTP sites cannot be more secure than an HTTPS site, even if untrusted. HTTP doesn't do encryption or identification. Phishers can make their sites on HTTP and no warnings are shown. In good faith, I am at the very least encrypting traffic. How can that be a bad thing?

Answer 1

They do that because a SSL certificate isn't just meant to secure the communication over the wire. It is also a means to identify the source of the content that is being secured (secured content coming from a man in the middle attack via a fake cert isn't very helpful).

Unless you have a third party validate that you are who you say you are, there's no good reason to trust that your information (which is being sent over SSL) is any more secure than if you weren't using SSL in the first place.

Answer 2

SSL provides for secure communication between client and server by allowing mutual authentication, the use of digital signatures for integrity, and encryption for privacy.

(apache ssl docs)

Yep, I don't see anything about third party certificate authorities that all browsers should recognize as "legit." Of course, that's just the way the world is, so if you don't want people to see a scary page, you've got to get a cert signed by someone the browsers will recognize.

or

If you're just using SSL for a small group of individuals or for in-house stuff, you can have people install your root cert in their browser as a trusted cert. This would work fairly well on a lan, where a network admin could install it across the entire network.

It may sound awkward to suggest sending your cert to people to install, but if you think about it, what do you trust more: a cert that came with your browser because that authority paid their dues, or a cert sent to you personally by your server admin / account manager / inside contact?

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Just for shits and giggles I thought I'd include the text displayed by the "Help me understand" link in the screenshot in the OP...

When you connect to a secure website, the server hosting that site presents your browser with something called a "certificate" to verify its identity. This certificate contains identity information, such as the address of the website, which is verified by a third party that your computer trusts. By checking that the address in the certificate matches the address of the website, it is possible to verify that you are securely communicating with the website you intended, and not a third party (such as an attacker on your network).

For a domain mismatch (for example trying to go to a subdomain on a non-wildcard cert), this paragraph follows:

In this case, the address listed in the certificate does not match the address of the website your browser tried to go to. One possible reason for this is that your communications are being intercepted by an attacker who is presenting a certificate for a different website, which would cause a mismatch. Another possible reason is that the server is set up to return the same certificate for multiple websites, including the one you are attempting to visit, even though that certificate is not valid for all of those websites. Chromium can say for sure that you reached , but cannot verify that that is the same site as foo.admin.example.com which you intended to reach. If you proceed, Chromium will not check for any further name mismatches. In general, it is best not to proceed past this point.

If the cert isn't signed by a trusted authority, these paragraphs follow instead:

In this case, the certificate has not been verified by a third party that your computer trusts. Anyone can create a certificate claiming to be whatever website they choose, which is why it must be verified by a trusted third party. Without that verification, the identity information in the certificate is meaningless. It is therefore not possible to verify that you are communicating with admin.example.com instead of an attacker who generated his own certificate claiming to be admin.example.com. You should not proceed past this point.

If, however, you work in an organization that generates its own certificates, and you are trying to connect to an internal website of that organization using such a certificate, you may be able to solve this problem securely. You can import your organization's root certificate as a "root certificate", and then certificates issued or verified by your organization will be trusted and you will not see this error next time you try to connect to an internal website. Contact your organization's help staff for assistance in adding a new root certificate to your computer.

Those last paragraphs make a pretty good answer to this question I think. ;)