Why 'This Connection is Untrusted' for practically every site on Mozilla Firefox?

Question

This started a couple of months ago and pops up for just about every site, including Google, Macy's, DSW, Outlook.com, etc. These are all regularly visited sites so there should be no problem. There is no problem if I use Chrome or Internet Explorer.

Searching for resolution has indicated the problem can be fixed by correcting the date/time or that it is due to issues with BitDefender.

Neither is my problem. My clock & date are connected to our network and are correctly displayed. There is no BitDefender installed on my machine.

Disabling the certificate validation is also recommended as a solution however, the problem still continued after following the steps to disable. I have also removed the program entirely from my computer and reinstalled it. Still running into the same issue.

Does anyone have a way to truly fix this ?

Thanks

Solution

I had this same problem and it started yesterday (6/22/2013) when my computer did an auto-update: "Mozilla FireFox 30.0 (x86 en-US)". I think that the update didn't download properly, or it was a corrupt file or something. I tried a bunch of things but most of the stuff I was finding on-line didn't work.

Uninstalling FireFox and re-installing the most recent version fixed the problem.

Go to your Control Panel; uninstall FireFox, then go to the FireFox website in another browser and re-install. That worked for me!

Comments

[TomEus]

Please post either screenshot or details of the certificate that shows as untrusted

[allquixotic]

It is possible that someone is doing something nasty (i.e., trying to man in the middle you). If so, they're doing a poor job of it; a good MITM will install the root cert of the attacker on your system so you never even see that warning dialog box. But it could still be an attack. Impossible to rule out based on the info you provided, although it's very odd that IE and Chrome work. The attack may be network-layer, so there may not even be a virus/malware on your own system; it could be on the network you're connected to. You'd need to run a packet capture or view the SSL cert to find out.

[Ramhound]

I just realized that it's chrome and ie that share the same store a malicious certs with just Firefox is indeed possible although unlikely if every website is blocked

[allquixotic]

@Ramhound Maybe the MITM attempt installed a malicious root cert into the IE/Chrome certificate store, but was too lazy or not smart enough to install it into Firefox's certificate store. You may be on to something there.

[tvdo]

@Ramhound You make a good point - Chrome and IE both use the Windows system store while Firefox maintains its own. A malicious attacker could have installed a cert in the system store. Incidentally, is this a company machine? It's fairly typical for companies to have DPI firewalls that perform HTTPS MITM, and they will install their own trusted root CAs in all company computers' system stores.

[Ramhound]

@Bob - IE and Firefox both can be configured to "hard fail" which means if they cannot verify the certificate path the connection won't be made. Chrome takes a different approach and can't be cnfigured in the same way although it will hard fail only on certain cases.

[Syberdoor]

Do you use Kaspersky IS? It has a feature where it replaces certain certificates that relies on the windows cert store and is thus incompatible with firefox by default (there is a solution though)

[Daniel B]

Dunno why this was downvoted so much. Certificates have a validity timespan and if your date is way off, almost all certificates will be “from the future”.