Removes/distrusts StartCom's certificate authorities in Firefox, desktop and mobile.


Removes/distrusts StartCom's certificate authorities in Firefox, desktop and mobile.

Copyright (C) 2014-2016 Scott Zeid. Released under the X11 License.
AMO · Releases on GitLab · Source code


This is an addon for Firefox and Firefox for Android that removes (or in the case of built-in certificates, distrusts) StartCom's certificate authorities from the certificate database. (StartCom is the company that operates a widely-known "free" StartSSL certificate authority.) This is necessary due to their hostile attitude towards customers affected by the infamous Heartbleed bug: they require us to pay US$24.90 per certificate in order to have them revoked, blaming us for the fact that we may have been compromised, and not offering any waiver or discount for users who have multiple certificates with them and cannot afford to revoke them all.

They are apparently waiving the revocation fee for (at least some) paying customers, but that means jack shit to me. StartCom has shown that they do not possess any common sense whatsoever, and that they are willing to let their users of lesser financial means suffer just because they want to make a quick buck off of a severe security bug that even they couldn't have anticipated. (There is no way it actually costs them US$24.90 just to revoke one certificate.) The only solution to this problem is to distrust StartCom.

Permanently. Because even if they change their minds in this one instance, they have already shown that they cannot be trusted with anyone's security.

(I am aware that revocations aren't as useful against many attacks, but it's better to protect users against some attacks than none. This may also be the reason that Mozilla and Debian have refused to remove StartCom's CAs themselves, but I disagree with those decisions, again because some protection is better than none. Furthermore, if revocations weren't as broken as they are now, I don't see how StartCom's policy would have been any different.)

This add-on does that for Firefox users, both on desktops and mobile. While this add-on is installed and enabled, StartCom's CA certificates will be removed/distrusted each time the browser is started, as well as each time the add-on is enabled. (Disabling or removing the add-on does not re-trust them, simply because I'm lazy; you will need to do that manually if you want to.)

This is useful for mobile users, as Firefox for Android doesn't have a graphical certificate manager (you can access the desktop's one via chrome://pippki/content/certManager.xul, but it's unusable on mobile), as well as for users or organizations with multiple Firefox installations who would like to distrust StartCom with the least effort possible.

Note: After installing this add-on, some StartCom certificate authorities may still appear in the certificate manager. These would be built-in certificates that cannot be removed, so instead they are distrusted. You can verify this by clicking on each certificate and then clicking "Edit Trust". None of the three checkboxes should be checked.

Note to server operators who (still) use StartCom

Now that Let's Encrypt is open to the public, there is absolutely no excuse to continue using StartCom. Destroy your old private keys and switch over now. If you're worried about how the client works, a couple of notes:

  • letsencrypt certonly --webroot -w <web-root> will let you get certificates without having to shut down your server temporarily. Just make sure that paths that start with /.well-known/acme-challenge/ get served from the web-root that you specify in the command (the client will create the .well-known subdirectory inside web-root). You can also have your server serve just the ACME challenge directory from a separate web root. The certonly part will also cause it to only get the certificate, so that you can install it manually.
  • You can also use HAProxy and the --tls-sni-01-port letsencrypt option to do TLS SNI validation on a separate port from your normal HTTPS server.
  • If you don't like giving the client root access, there are plenty of other clients—and libraries for many programming languages—available. Knock yourself out.
  • If you can't or don't want to generate certificates on the server itself, (at least) the official client has a manual mode that lets you do it from another machine.
  • If you're worried about 90-day lifetimes, they're working on making automated renewals easier. In the meantime, set up a cron job and pass the --renew-by-default flag to letsencrypt.