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Ask HN: How bad is it to use a self-signed SSL certificate?

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Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#81

Post by Istof »

ctz wrote: post #20

If you are careful when generating your certificate (that is, careful to generate a subject certificate, and not a CA certificate) and can reliably distribute your certificate to all clients you are interested in , then self-signed certificates are usually much better than the public CA system . But actually achieving the pre-distribution step is pretty hard, and basically impossible over the internet. You can achiev…

yes, this is my biggest problem with my favorite browser... why does Firefox do this? (Encrypted, unauthenticated: THE SKY IS FALLING.) edit: this is probably part of a NSL...

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#82

Post by MichaelGG »

mindslight wrote: post #51
tptacek wrote: post #23

Earlier quoted context omitted.

A site claiming to offer cryptographic security when it is in fact not is, in reality, worse than a site that simply doesn't offer cryptographic security. Both those sites --- the SSL site and the non-SSL site --- aren't offering security. But only one of them is also being deceptive about it. However, you'll get no argument from me if you constrain your argument about dismal mis-design to browser UI/UX. The browser…

Unauthenticated SSL does provide security against passive attackers , which is what mass surveillance in developed countries is. If the NSA ever insists on widespread MITM of connections, we have much bigger problems. I agree the UI needs to be properly worked out so that eg a bank can't be downgraded to an unauthenticated certificate.

That's the whole point: There's no way to determine "unauthenticated" SSL versus MITM SSL. Once you have that "worked out" then you've solved the issue of self-signing in the first place.

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#83

Post by MichaelGG »

digitalchaos wrote: post #77
Silhouette wrote: post #65

Earlier quoted context omitted.

That's perfectly fair and reasonable from a commercial perspective. From a security perspective, however, I think you need to meet some minimum standards to remain credible as a CA, and I think at least being willing to revoke certificates that may have been compromised for free and very quickly is one of those standards. I find it difficult to support retaining StartSSL certificates as trusted-by-default in browsers…

That's understandable and probably a good reason for startssl to build an automated revoke tool, for the sake of keeping their name healthy. However, I would be way more concerned about a company unwilling to pay a trivial amount of money to revoke a cert that was compromises due to their own choice in how they used it. The best CA in the world won't fix bad security incident handling of another company. Sure, most o…

I'm surprised it's not a requirement of being a CA. Further speaks to the apparently weak standards the browsers have.

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#84

Post by MichaelGG »

pbreit wrote: post #22
cjbprime wrote: post #2

It's terrible, because Man-In-The-Middle attacks are trivial and automatable. namecheap.com sells PositiveSSL certs for $9/year -- that's pretty cheap and easy.

What could be achieved with a MitM attack on an information-only site?

Finding out what someone is interested in. Search queries or specific articles. Determining their browser information.

If the site is particularly trusted (say, a news site), misleading users into trusting another party. If CNN ran an article about how adding some SSL cert to your trust store would make YouTube faster, a lot of people would do it.

Or you could directly attack the user by providing false information.

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#85

Post by MichaelGG »

yaur wrote: post #56
dvanduzer wrote: post #28

Earlier quoted context omitted.

This is true, but you wouldn't believe the system-as-practiced by most large IT departments. edit: small IT departments, too. nobody really pays attention as long as the lock icon is green.

Can't speak to the state of this on Linux, but on Windows/IIS if you "just follow the wizard" and send the generated file to your CA it will not include the key.

Some CAs offer a "service" that will generate the key and sign it for you. So you just follow the CA's wizard and never generate a key locally.

I saw a sorta tech-savvy person doing this and they didn't see anything wrong with it. It's yet another thing that CAs should not be allowed to do but get away with anyways.

Most people setting up web pages simply have no idea what's going on with a CSR. It's all some weird files to them. Most of them probably think the key is included in the certificate the CA sends you.

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#86

Post by MichaelGG »

romanovcode wrote: post #61
markgamache1 wrote: post #46

YOU ARE DESTROYING THE INTERNET Training users, who have no way to properly asses this risk, to click OK to the SSL error, is like Jim Jones's practice runs drinking the Koolaide. Firefox had it right when the briefly made it impossible to OK the use of misconfigured SSL. Most IT people don't understand the risk of self-signed certs. We can't expect users to make good choices here.

It's still more secure than plain-text http tho.

Since there's no way to distinguish MITM and an unverified certificate, it can make people think they are secure when they are not. That's not "more secure".

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#87

Post by yaur »

chimeracoder wrote: post #76
YZF wrote: post #75

Earlier quoted context omitted.

The problem is that the people who can understand what you said don't ask questions about self signed certificates and the people who don't understand will somehow interpret this as support for using self signed certificates when you don't have an out-of-band method of getting your public key out. It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where the…

> It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where they're used... No, but it's not easier, either - without verification, it's exactly the same. It's not meaningful to try and make SSL secure in the situation in which out-of-band verification cannot be done. If there is no out-of-band verification, all SSL fails to protect against MITM. At the very…

WiFi attacks are not necessarily passive, ARP poisoning can redirect a victim's traffic to your machine at which point you can MITM to your hearts content. If you have trained your users to ignore the inevitable security warning (Grandma isn't going to check an SSL fingerprint) they are going to be operating under the false assumption that their communications are secure. For most people this is a worse scenario than the NSA having their data.

If you are talking about a thick client, with the appropriate checks built in, I'll agree that it's possibly more secure. Other than that, its only possibly more secure if you are the only user or you can eliminate the security warning (e.g. by distributing the certificate).

I'm skeptical that any US based company could get away with not rolling in the face of a subpoena/NSL so the protection provided by the service provider knowing they have been compromised is minimal IMO.

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#88

Post by 13throwaway »

MichaelGG wrote: post #82
mindslight wrote: post #51

Earlier quoted context omitted.

Unauthenticated SSL does provide security against passive attackers , which is what mass surveillance in developed countries is. If the NSA ever insists on widespread MITM of connections, we have much bigger problems. I agree the UI needs to be properly worked out so that eg a bank can't be downgraded to an unauthenticated certificate.

That's the whole point: There's no way to determine "unauthenticated" SSL versus MITM SSL. Once you have that "worked out" then you've solved the issue of self-signing in the first place.

I think I have a good idea to solve this. What if a system similar to HSTS was implemented? https://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security important sites (banks) could send a "don't allow self signed certs" header. Browser UI could change to educate users not to type personal information into self signed sites.

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#89

Post by psykovsky »

mindslight wrote: post #52
lockes5hadow wrote: post #49

Earlier quoted context omitted.

You have a point here. Perhaps the real solution is that we should make the browser throw a fit when someone tries to input a "password" into a page/authdialog that has no security as well.

Then the altered page just specifies that it is not a password field, and emulates it with javascript or whatever. So that could only work for sites where a password manager was used, assuming the user doesn't just go ahead and type it in themselves.

Not just passwords, any form submission. :P

Re: Ask HN: How bad is it to use a self-signed SSL certificate?

#90

Post by YZF »

chimeracoder wrote: post #76
YZF wrote: post #75

Earlier quoted context omitted.

The problem is that the people who can understand what you said don't ask questions about self signed certificates and the people who don't understand will somehow interpret this as support for using self signed certificates when you don't have an out-of-band method of getting your public key out. It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where the…

> It's not harder to MITM a self signed cert when it's validty can't be verified which is 99.99% of the use cases where they're used... No, but it's not easier, either - without verification, it's exactly the same. It's not meaningful to try and make SSL secure in the situation in which out-of-band verification cannot be done. If there is no out-of-band verification, all SSL fails to protect against MITM. At the very…

I see snooping as a lesser concern. For one thing the three letter agency snooping somewhere on the backbone can't even see the identity of the parties involved. They will typically see NATted IPs on both ends of some service provider. Once they decode the protocol they can get a little more information but at the end of the day the difference between knowing you established an SSL connection with respect to some static site and seeing the actual content of the page that you've viewed is IMO not a big difference.

The bigger deal is the confusion it creates and the assumptions a lot of the users of self signed certs (and certs in general) make about security.

Lastly I want to point out that if your certificate is signed by some external entity that doesn't prevent you from doing out-of-band management of your public key. As long as your private key is secret you never lose any security by having your cert signed by a third party. People can argue about how secure that signature is vs. those agencies who can force the third party to reveal their secret key but while that's an important consideration, until the government sells my banking information to somebody I mostly care about this at a principle level.

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