This protection works with a list provided by Google and thus can change at any time when Google updates this list.

• https://support.mozilla.org/en-US/kb/how-does-phishing-and-malware-protection-work
• https://support.mozilla.org/en-US/kb/where-find-and-manage-downloaded-files-firefox

The question wasn't answered. Does Firefox get the updates with every new update of firefox itself meaning the content is already built into every Firefox or does Firefox periodically check a database and update when requireded?

The list is updated in Firefox when the list is updated on Google. It works just like sync.

Sync must go out to the network to get the required information. Is this correct?

The web site https://watch-series.io/ was flagged as a bad web site and today Feb-13-2018 no notification.

Can an explanation be provided? Can the google flagged site be viewed?

I think there is an internal polling schedule built into Firefox. If you look at the preferences list:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste safeb and pause while the list is filtered

You'll notice the following bolded preferences with long numeric values -- I've given mine as examples:

• browser.safebrowsing.provider.google4.lastupdatetime
  • 1518551081140 => Tuesday, February 13, 2018 11:44:41.140 AM

• browser.safebrowsing.provider.google4.nextupdatetime
  • 1518552875140 => Tuesday, February 13, 2018 12:14:35.140 PM

• browser.safebrowsing.provider.mozilla.lastupdatetime
  • 1518549282490 => Tuesday, February 13, 2018 11:14:42.490 AM

• browser.safebrowsing.provider.mozilla.nextupdatetime
  • 1518552882490 => Tuesday, February 13, 2018 12:14:42.490 PM

So that implies an update frequency of 30-60 minutes. However, we know there is a delay between the time bad sites are reported to Google and when they get blocked, so even if Firefox is checking for updates frequently, the list might not actually be updated that often.

P.S. I used this site to convert that long number to my local time: https://www.epochconverter.com/

mace2 said

The web site https://watch-series.io/ was flagged as a bad web site and today Feb-13-2018 no notification. Can an explanation be provided? Can the google flagged site be viewed?

Google documents its evaluation here: https://transparencyreport.google.com/safe-browsing/search?url=watch-series.io

Thanks jscher2000. However I am a bit disappointed that firefox doesn't use its own database instead of google. Since Firefox does record bad web sites.