Current system for SSL certs has failed hard, in principle and empirically

http://permalink.gmane.org/gmane.comp.encryption.general/14253

by bensummers • 16 years ago

28 25 16 years ago

permalink.gmane.org

rlpb3• 16 years ago

> Of 16 M IPs listening on 443, 10.8 M started SSL handshake; of those, 4.3 M used CA-signed cert chains (slide 14). Thus, the majority of servers use "invalid"/invalid/self-signed certs.

How many of these IPs listening on 443 are public web servers? I know of a lot of things that listen for SSL on 443 that aren't HTTP as 443 can get through firewalls easily. For all we know, there already exists an out-of-band process to validate those self-signed certs.

For example, I am one of these cases. I listen for SSL on port 443 using a self-signed cert, but all clients have that CA (and only that CA) pre-loaded.

rlpb3• 16 years ago

In addition, it occurs to me that I've observed many sites that aren't security critical but seem to be running on a self-signed cert. For example, many mailing list archives seem to operate both on HTTP and HTTPS with a self-signed cert. As they are only hosting public data and clearly are happy to provide it without SSL as well, there is no security failure here.

klync5• 16 years ago

I think you would still have to count that as a security failure. For one, you don't know why there is ssl and non-ssl - there could be content that's available over ssl and/or via login which you don't see using the "public" http url schema. The server could be set up to make this transparent to you, making it appear that ssl is superfluous. Second, even if that's the case, a broken SSL implementation is still a broken SSL implementation, even if it's protecting content that doesn't seem to need protecting.

bensummers• 16 years ago

Access to our non-public systems is (partially) controlled through SSL server and client certificates, both of which use a CA we control. This is probably a good practise for systems you are keen on defending, because the public CA system is so broken.

JunkDNA• 16 years ago

I think there are a lot of site owners who make the mistake of thinking that SSL is only about encryption. They see these certs as a way to prevent data snooping. It's easy to see when a browser doesn't show a little lock icon or warns about an untrusted cert. The identity management side that protects against outright website forgery is harder to police and largely hidden from end users and customers of the CA's. As a result, there is probably insufficient pressure on the CA's to pay attention to some of this stuff.

tbrownaw2• 16 years ago

The identity management side that protects against outright website forgery is harder to police and largely hidden from end users and customers of the CA's

If it's hidden from end users, how the hell can it actually work?

As a result, there is probably insufficient pressure on the CA's to pay attention to some of this stuff.

All that matters is the one CA that pays the least attention, and I don't see how site owners have any control over that.

StavrosK• 16 years ago

I am very much partial to the Perspectives way of doing SSL authentication:

http://www.cs.cmu.edu/~perspectives/firefox.html

I don't need to know if the guy has paid someone to sign their certificate, I need to know if that certificate has been there for longer (even if it's self-signed). It's just more valuable information than whether or not a guy has $10.

I really hope Perspectives becomes standard in all browsers, then we can slowly migrate away from central signing CAs.

klync5• 16 years ago

I've used a self-signed cert for years, and eventually I got over being annoyed at browsers for lying to users and telling me that the cert was not to be trusted. The fact is, as I'm sure most at HN know, that SSL tries to solve two problems - identity and encryption. We definitely need a better way to validate a site's identity. I hope this study provides a kick in the pants toward that end.

robryan• 16 years ago

It's a tradeoff I guess, at the low end people don't want to provide documents, wait and pay a decent amount to get their identity verified.

Maybe it would be best to separate them, you can self sign or equivalent for encryption and the identity system can be separate.

Retric2• 16 years ago

There is little point in encrypting traffic if you can't differentiate between a man in the middle and your desired endpoint.

EX: Conceder I open encrypted connection to amazone.com which pretends to be amazon.com they open an encrypted connection to amazon.com. Amazone can now pretend to be Amazon and read all my encrypted traffic.

tbrownaw2• 16 years ago

You need some amount of identity checking, to tell you that the https://uncesnsored.citadel.org/ you're talking to today is the same one you were talking to yesterday and last week. SSH handles this by remembering the key used on the first connection; Perspectives goes one better and checks from multiple parts of the network.

Tying these online identities to physical-world identities is what can be separate.

arethuza2• 16 years ago

Why do you think browsers were "lying" when they said the certificate wasn't to be trusted? Without any kind of "trusted third party" involved there is no reason at all to trust your self signed certificate.

klync5• 16 years ago

Fair question. I just checked what exactly the warning message says in IE, and it's actually a pretty fair warning message. Firefox, on the other hand, has a pretty scary "This connection is untrusted" page with a pretty confusing explanation of the alleged problem. I don't know if this still happens, but I remember a couple years ago, it was impossible to get IE or Firefox to actually save the cert or remember your preference to bypass the warning, so you would get the warning each time you had a new browser session and tried to connect to the server, no matter what.

The fact is, my real-life identity was never verified as the owner of the domain by a "trusted" third party. However, the encryption key comes from the same server serving the content, so what, really, is not to be trusted? I.e. the cert applies to "domain.com" and is being used on "domain.com". There is no risk of MITM attack, only that "domain.com" is not what you think it is.

JoachimSchipper3• 16 years ago

OTOH, Firefox - and other browsers - make a self-signed or expired SSL certificate look extremely scary, while a totally unencrypted connection is fine. I understand the reason, but it´s still odd...

Current system for SSL certs has failed hard, in principle and empirically

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