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How to solve certificate interception on work computer?

  • 3 replies
  • 3 have this problem
  • 9 views
  • Last reply by cor-el

utku1
utku1
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I am encountering the "The certificate is not trusted because the issuer certificate is unknown." on each and every website I try to visit. Even in google.com.

I am on a computer at work. I have browsed the internet for a fix and as of the answer of [this question](https://support.mozilla.org/en-US/questions/1032509), I am guessing that the problem is the interception of my network connection by some program.

However, I don't know what I can do to solve this problem. Probably trying to stop the interception of my network is not possible since that would be against the company policies. So, is there any way to use the Firefox properly at work? What can I do to get it working?

Best regards

I am encountering the "The certificate is not trusted because the issuer certificate is unknown." on each and every website I try to visit. Even in google.com. I am on a computer at work. I have browsed the internet for a fix and as of the answer of [this question](https://support.mozilla.org/en-US/questions/1032509), I am guessing that the problem is the interception of my network connection by some program. However, I don't know what I can do to solve this problem. Probably trying to stop the interception of my network is not possible since that would be against the company policies. So, is there any way to use the Firefox properly at work? What can I do to get it working? Best regards

All Replies (3)

the-edmeister
the-edmeister
  • Moderator
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Beyond the information provided here: https://support.mozilla.org/en-US/questions/1032509

See this support article: https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

I trust that is happening with secure websites (HTTPS) only. If that happens at all websites (including non secure HTTP websites) you have something else going on. The most common problem on desktop devices is the date, time, and time zone setting in Windows being incorrect. That can happen when the 'coin battery' on the motherboard is dead or very weak and it won't "remember" the setting in the operating system when the PC is turned off or has no power.

utku1
utku1 Question owner
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Exactly. Just checked now and it indeed happens only on HTTPS websites.

I had already looked at the second link but it didn't help. I am getting "The certificate is not trusted because the issuer certificate is unknown." error. Deleting "cert8.db" did not help.

Unfortunately first link did not help much as well. Because since there is no "Add Exception" button, I am not able to see by whom the certificate is issued.

What should I do?

cor-el
cor-el
  • Moderator
  • Top 10 Contributor
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There is security software like Avast and Kaspersky and BitDefender that intercept secure connections and send their own certificate.

If you can't inspect the certificate via "I Understand the Risks" then try this:

Open the "Add Security Exception" window by pasting this chrome URL in the Firefox location/address bar and check the certificate:

  • chrome://pippki/content/exceptionDialog.xul

In the location field of this window type or paste the URL of the website.

  • retrieve the certificate via the "Get certificate" button
  • click the "View..." button to inspect the certificate in the Certificate Viewer

You can inspect details like the issuer and the certificate chain in the Details tab of the Certificate Viewer. Check who is the issuer of the certificate. If necessary then you can attach a screenshot that shows the certificate viewer.