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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?

#71

Post by rhizome »

Spittie wrote: post #13

https://www.startssl.com/ gives out free SSL certificates. Just don't expect much on their part, given it's free. For example, they refused to reissue certificates for free after Heartbleed. Also you can't use them on commercial sites. otherwise https://www.gogetssl.com/ is probably as cheap as it gets.

Not to mention their inscrutable information and documentation. I was caught out trying to renew a StartSSL cert 6mos ago and could not even access the renewal site. Apparently they use personal certs (or the cert I got?) as authentication? I don't know, because there was no explanation, anywhere. I had no idea whether this is security by obscurity or what, but f-them. I wound up paying $5 to Comodo and having a somewhat more comfortable experience, at least to the degree that there's a standard user control panel and payment flow.

Looks like maybe StartSSL filled out their FAQ a little since then, but only a little:

https://www.startssl.com/?app=25#10

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

#72

Post by benatkin »

You should quit using them if anyone other than you ever needs to open the page in a browser. The warnings will never be good enough for partial clicking through of them. If a user (even a technical one) gets talked into clicking through an SSL error, it is likely that they have been talked into a bad habit.

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

#73

Post by Osmium »

chimeracoder wrote: post #69
Osmium wrote: post #67

Earlier quoted context omitted.

Off-topic, but speaking of spurring adoption of DNSSEC: does anyone know of any good (dumbed-down) guides on setting up DNSSEC on personal domains / using dnssec-keygen? I keep seeing it mentioned in HN threads as a Good Thing, and I know my registrar supports it, but they have a big warning: "It is strongly recommended that you do not enable this option unless you have a good understanding of what it is and does: yo…

> I keep seeing it mentioned in HN threads as a Good Thing, Opinions on DNSSEC are... mixed, to say the least: https://news.ycombinator.com/item?id=5571937 As a small website owner, are you using TLS? That's the biggest single thing you should be doing - don't worry about DNSSEC. This depends on what you mean by "small", but IMHO, you don't need DNSSEC. Depending on how small/important your website is, you probably d…

Thanks for the link; that's actually very informative. My interest in DNSSEC came from reading that it provided a mechanism to securely transmit SSH host key fingerprints, though I'm not sure if there's a better way of doing that.

> As a small website owner, are you using TLS?

Yes, but I don't require it. Just a free certificate from StartSSL.

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

#74

Post by zhovner »

Osmium wrote: post #67
blumentopf wrote: post #63

If your zones are signed with DNSSEC, just add a TLSA record for the self-signed certificates to the zones. Clients with DANE [1] support will then recognize that the self-signed certificates are valid. Of course, very few clients support DANE as of yet. Nevertheless, that is the most modern solution and you'll spur adoption of DNSSEC and DANE if you offer it to clients. [1] https://tools.ietf.org/html/rfc6698

Off-topic, but speaking of spurring adoption of DNSSEC: does anyone know of any good (dumbed-down) guides on setting up DNSSEC on personal domains / using dnssec-keygen? I keep seeing it mentioned in HN threads as a Good Thing, and I know my registrar supports it, but they have a big warning: "It is strongly recommended that you do not enable this option unless you have a good understanding of what it is and does: yo…

Try this https://translate.google.com/translate?sl=ru&tl=en&js=y&prev...

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

#75

Post by YZF »

chimeracoder wrote: post #64
yaur wrote: post #54

Earlier quoted context omitted.

I'm going to go out on a limb here and say that the vast majority of that 0.2% are people sitting behind corporate proxies with a fake CA cert installed and pushed out to workstations via Group Policy. A hostile (and targeted) MITM could remove or alter the JavaScript that posts the fingerprint back to the server in which case it would be very difficult to detect. The problem with Self Signed Certs in a practical sen…

> The problem with Self Signed Certs in a practical sense is that they enable a much broader range of attacks. Neither of them protect you from LEO and NSA. This phrasing is misleading. Self-signed certs will protect against passive attackers, assuming the certificate can be verified out-of-band[0]. If the validity of a self-signed certificate cannot be verified, yes, it could be issued by a MITM. But it still protec…

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 they're used...

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

#76

Post by chimeracoder »

YZF wrote: post #75
chimeracoder wrote: post #64

Earlier quoted context omitted.

> The problem with Self Signed Certs in a practical sense is that they enable a much broader range of attacks. Neither of them protect you from LEO and NSA. This phrasing is misleading. Self-signed certs will protect against passive attackers, assuming the certificate can be verified out-of-band[0]. If the validity of a self-signed certificate cannot be verified, yes, it could be issued by a MITM. But it still protec…

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 least, it protects against passive snooping (ie, the NSA).

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

#77

Post by digitalchaos »

Silhouette wrote: post #65
digitalchaos wrote: post #60

Earlier quoted context omitted.

If you read startssl'a justification on the free cert, you'll see that they charge in relation to the time they need to spend. A low level 1 year cert involves no human time. They don't have fully automated systems for revokes/reissues, so it's pretty lame for people to complain about them charging for it.

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 of the complaining was due to the entitlement, but I'd be interested in a list of all the companies that complained about this and/or failed to pay for a revoke.

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

#78

Post by mindslight »

chimeracoder wrote: post #66
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.

I don't understand why they don't just use different colors for self-signed SSL connections. CA-signed: Green lockpad Self-signed: Yellow lockpad, with question mark superimposed over it Regular HTTP: Orange, no lockpad (insecure) Invalid or revoked cert: Red, "stay away" displayed within tags. The current UI that most browsers present implies that self-signed certificates are worse ("scarier") than regular HTTP, whi…

Well, it's not really a continuum. 'There should be only one mode, secure' and all that - asking users to make ad-hoc security assessments is generally a bad idea. In an ideal world, plaintext HTTP wouldn't exist and everyone would have a key delegated by their domain registrar.

No lock would suffice for unauthenticated https; those that find the distinction meaningful can investigate the URL. But then you still risk someone bookmarking https://example.com and suffering a downgrade attack from not paying attention to color changes.

The best way forward is probably the creation of a new protocol designator (httpz or something) that is SSL using the SSH key model. But there's no impetus to do this as it's easy enough to pay the CA tax and be on your way with unquestioned "full security".

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

#79

Post by asutherland »

kamaln7 wrote: post #8
nmb wrote: post #4

Earlier quoted context omitted.

You might be able to use StartSSL's free one: https://www.startssl.com/

Just keep in mind that Class 1 (free) certificates are for non-commercial sites only.

Wow! This surprised me since https://www.startssl.com/?app=1 makes no mention of this, but indeed section 3.1.2.1 of the StartCom CA policy at https://www.startssl.com/policy.pdf does state:

"Class 1 certificates are limited to client and server certificates, whereas the later is restricted in its usage for non-commercial purpose only. Subscribers MUST upgrade to Class 2 or higher level for any domain and site of commercial nature, when using high-profile brands and names or if involved in obtaining or relaying sensitive information such as health records, financial details, personal information etc."

Looking further, it appears that while these classifications are not formally encoded (that I can find after a cursory investigation; please let me know if I am wrong), it does appear to be the case that the concept/nomenclature exists amongst multiple CAs. Wikipedia context: http://en.wikipedia.org/wiki/Public_key_certificate#Classifi..., Indian Government CA policy: http://cca.gov.in/cca/?q=node/45

Thanks for pointing this out, as I have been erroneously indicating that the StartCom free certificates might be viable options in all cases, where it seems like the reality is somewhat different. (Although I still believe the barrier to usage of valid/non-self-signed certificates to be quite low and for it to be strongly advisable for server operators to use them.)

(edit note: inserted the missing word "been" shortly after submitting.)

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

#80

Post by asutherland »

blumentopf wrote: post #63

If your zones are signed with DNSSEC, just add a TLSA record for the self-signed certificates to the zones. Clients with DANE [1] support will then recognize that the self-signed certificates are valid. Of course, very few clients support DANE as of yet. Nevertheless, that is the most modern solution and you'll spur adoption of DNSSEC and DANE if you offer it to clients. [1] https://tools.ietf.org/html/rfc6698

Also somewhat off-topic but interesting in the context of DANE and the cost of certificates. Brian Smith (a mozilla security contributor) recently said the following in a discussion about adding support for invalid/self-signed certificates to the Firefox OS e-mail app. The quote below can be found at the bottom of https://groups.google.com/d/msg/mozilla.dev.platform/lT4Mhi-... noting that I think the first TLS is meant to be TLD.

"Regarding DANE: Any TLS registry can apply to be a trust anchor in Mozilla's CA program and we'll add them if they meet our requirements. We can constrain them to issuing certificates that are trusted only for their own TLDs; we've done this with some CAs in our program already. Any CA can give away free certificates to any subset of websites (e.g. any website within a TLD). Consequently, there really isn't much different about the CA system we already have and DANE, as far as the trust model or costs are concerned."

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