5 ms·

Self-signed SSL Certificates

23 points by joshbetz 15y ago

darklajid 15y ago
Why? Startssl gives you the same thing for free (as in beer), without the popup and without training users to ignore the warnings. I'm not a fan of certificate authorities in the first place, but for now they seem to be a good compromise between playing along and not throwing your savings at some snakeoil sellers..
eli 15y ago
1) training people to ignore browser SSL messages in any situation is, I think, not such a great idea, and 2) those warnings are there for a reason. How do you know that it's your self-signed cert you're being presented with and not a MITM attack? Do you check the fingerprint? Is your browser set up to warn you if the cert has changed since the last time you logged in?
alexchamberlain 15y ago
You could install your public certificate on your computer, rather than ignore the warnings.
- Kudos 15y ago
  s/could/should/
rshm 15y ago
Installing http://convergence.io/ http://convergence.io/ will solve the certificate warning problems.
tptacek 15y ago
Self-signed certificates are fine for "personal" use (ie, to give a small number of people an encrypted channel to something like an admin console). But "making sure the certificate was generated properly" is not the only thing Verisign is doing. The other thing Verisign does is sign your certificate for you. The reason that matters is that in the wild, any attacker that can see packets or control DNS can MITM your SSL connections. When they do that, they too will present a valid-looking "self-signed" certificate. The way your browser "breaks the tie", or tells the good cert from the bad one, is to check to see if the cert is properly signed all the way back up to a browser root. Again, this is fine in a personal setting: just accept the cert the first time you log in. As long as you're not getting the warning every time, you'll be fine. But it's not fine when you're talking about thousands of people hitting a public service. (Strong agree with upthread comment about installing Convergence).
joshbetz 15y ago
I definitely never meant to suggest that training people to ignore security warnings was the right way to do anything. I've updated to the post to note that you would be required to install the certificate locally to be certain that it's actually the correct cert. I appreciate the suggestions for free options. There have been some people that have problems with these services in the past, but I'll definitely look into them.
newman314 15y ago
I wouldn't say insanely secure. http://blog.trendmicro.com/2010s-most-dangerous-list/ http://blog.trendmicro.com/2010s-most-dangerous-list/ Keeping your WP install up to date is going to go a long way in helping secure things. Second, the comment about using StartSSL instead of a self-signed cert. Also, make sure you are using a sane config of ciphers. I've seen too many site where SSL is set up but the cipher list is set to the most insecure possible due to lack of configuration. It's not that hard and actually makes the use of SSL usable.
- tptacek 15y ago
  The cipher list is a good point, but know that this is a sev:low vulnerability; attackers aren't generally busting out brute forcers even for the 40-bit export ciphers.
  - newman314 15y ago
    Agreed but I have found customers with TLS_DH_anon_WITH_RC4_128_MD5 enabled for example. =( It's much more likely for a vulnerability with WP code than with cipher but I just wanted to point out the importance of properly setting ciphers. Besides with AES-NI avail, it's much less CPU intensive so another win.
    - tptacek 15y ago
      That ciphersuite has no viable attacks. Many sites switched to RC4 recently to deal with browser susceptibility to CBC repeated-IV problems.
zupreme 15y ago
I think the OP is dead on. The goal here is to encrypt your connection, not to bypass industry-standard security measures. Once you install the cert (client-side) you are protected just as you would be with a publicly signed cert. If you are ever subjected to a Man-In-The-Middle attack or a spoofing attempt, the exact same flags would occur. This is not a solution for eCommerce, or for your web-app's user sign-in page. This is for your admin panel and backend which only you (or your staff if you have one) will be using. If you actually install the cert to your local certificate store (as opposed to just cancelling out of the alert) you should be solid. Great post Josh.
- AjithAntony 15y ago
  Another detail he kinda neglected, is that if you don't want browser warnings, the then common name of the subject(or an alt name) needs to match the host the user connects to. Having a cert for "www.joshbetz.com" in your cert store does not preclude the warnings about the host name mismatch when you visit joshbetz.com/
  - joshbetz 15y ago
    Thanks for pointing that out. Safari wasn't giving me any warnings, but Chrome definitely does.
JohnTHaller 15y ago
You can't really trust the opinion of someone who leads with: "I use WordPress and it’s insanely secure". It's not. It has serious security bugs in it which allow full web server access on a fairly regular basis. You need to keep it up to date and subscribe to the announcement list to ensure you don't miss an update, just like you do with any content management system.
- joshbetz 15y ago
  All updates are one-click and it tells you when updates are available. I don't see a problem with expecting people to keep their software up-to-date. I don't know of any software that is secure forever without ever worrying about updates.
  - JohnTHaller 15y ago
    One-click updates are great, if you happen to be logged into your site that day. You need to subscribe to the announce list and get the info sooner for days when you are not. Same as with any CMS. And I never said there was a problem with expecting people to keep their software up to date. Just that it doesn't happen automatically. People have to do it. And I know a lot of people with outdated Wordpress installs. That's the reason behind the recent news of 60,000 Wordpress sites being hacked. Wordpress is pretty secure if you keep it up to date and monitor when updates happen. But saying it is 'insanely secure' is simple ludicrous.

23 points by joshbetz 15y ago

Why? Startssl gives you the same thing for free (as in beer), without the popup and without training users to ignore the warnings. I'm not a fan of certificate authorities in the first place, but for now they seem to be a good compromise between playing along and not throwing your savings at some snakeoil sellers..

eli 15y ago

1) training people to ignore browser SSL messages in any situation is, I think, not such a great idea, and 2) those warnings are there for a reason. How do you know that it's your self-signed cert you're being presented with and not a MITM attack? Do you check the fingerprint? Is your browser set up to warn you if the cert has changed since the last time you logged in?

alexchamberlain 15y ago

You could install your public certificate on your computer, rather than ignore the warnings.

Kudos 15y ago
s/could/should/

rshm 15y ago

Installing http://convergence.io/ http://convergence.io/ will solve the certificate warning problems.

tptacek 15y ago

Self-signed certificates are fine for "personal" use (ie, to give a small number of people an encrypted channel to something like an admin console). But "making sure the certificate was generated properly" is not the only thing Verisign is doing. The other thing Verisign does is sign your certificate for you. The reason that matters is that in the wild, any attacker that can see packets or control DNS can MITM your SSL connections. When they do that, they too will present a valid-looking "self-signed" certificate. The way your browser "breaks the tie", or tells the good cert from the bad one, is to check to see if the cert is properly signed all the way back up to a browser root. Again, this is fine in a personal setting: just accept the cert the first time you log in. As long as you're not getting the warning every time, you'll be fine. But it's not fine when you're talking about thousands of people hitting a public service. (Strong agree with upthread comment about installing Convergence).

joshbetz 15y ago

I definitely never meant to suggest that training people to ignore security warnings was the right way to do anything. I've updated to the post to note that you would be required to install the certificate locally to be certain that it's actually the correct cert. I appreciate the suggestions for free options. There have been some people that have problems with these services in the past, but I'll definitely look into them.

newman314 15y ago

I wouldn't say insanely secure. http://blog.trendmicro.com/2010s-most-dangerous-list/ http://blog.trendmicro.com/2010s-most-dangerous-list/ Keeping your WP install up to date is going to go a long way in helping secure things. Second, the comment about using StartSSL instead of a self-signed cert. Also, make sure you are using a sane config of ciphers. I've seen too many site where SSL is set up but the cipher list is set to the most insecure possible due to lack of configuration. It's not that hard and actually makes the use of SSL usable.

tptacek 15y ago
The cipher list is a good point, but know that this is a sev:low vulnerability; attackers aren't generally busting out brute forcers even for the 40-bit export ciphers.
- newman314 15y ago
  Agreed but I have found customers with TLS_DH_anon_WITH_RC4_128_MD5 enabled for example. =( It's much more likely for a vulnerability with WP code than with cipher but I just wanted to point out the importance of properly setting ciphers. Besides with AES-NI avail, it's much less CPU intensive so another win.
  - tptacek 15y ago
    That ciphersuite has no viable attacks. Many sites switched to RC4 recently to deal with browser susceptibility to CBC repeated-IV problems.

zupreme 15y ago

I think the OP is dead on. The goal here is to encrypt your connection, not to bypass industry-standard security measures. Once you install the cert (client-side) you are protected just as you would be with a publicly signed cert. If you are ever subjected to a Man-In-The-Middle attack or a spoofing attempt, the exact same flags would occur. This is not a solution for eCommerce, or for your web-app's user sign-in page. This is for your admin panel and backend which only you (or your staff if you have one) will be using. If you actually install the cert to your local certificate store (as opposed to just cancelling out of the alert) you should be solid. Great post Josh.

AjithAntony 15y ago
Another detail he kinda neglected, is that if you don't want browser warnings, the then common name of the subject(or an alt name) needs to match the host the user connects to. Having a cert for "www.joshbetz.com" in your cert store does not preclude the warnings about the host name mismatch when you visit joshbetz.com/
- joshbetz 15y ago
  Thanks for pointing that out. Safari wasn't giving me any warnings, but Chrome definitely does.

JohnTHaller 15y ago

You can't really trust the opinion of someone who leads with: "I use WordPress and it’s insanely secure". It's not. It has serious security bugs in it which allow full web server access on a fairly regular basis. You need to keep it up to date and subscribe to the announcement list to ensure you don't miss an update, just like you do with any content management system.

joshbetz 15y ago
All updates are one-click and it tells you when updates are available. I don't see a problem with expecting people to keep their software up-to-date. I don't know of any software that is secure forever without ever worrying about updates.
- JohnTHaller 15y ago
  One-click updates are great, if you happen to be logged into your site that day. You need to subscribe to the announce list and get the info sooner for days when you are not. Same as with any CMS. And I never said there was a problem with expecting people to keep their software up to date. Just that it doesn't happen automatically. People have to do it. And I know a lot of people with outdated Wordpress installs. That's the reason behind the recent news of 60,000 Wordpress sites being hacked. Wordpress is pretty secure if you keep it up to date and monitor when updates happen. But saying it is 'insanely secure' is simple ludicrous.