I'd search for this in the Firefox extension list myself if I knew what "nuisance in-page overlay popups" are formally known as.
Usually they darken or blur the rest of the web page behind them and put up a popup box in the middle of the screen that you have to click to remove. These can be dangerous if someone embeds a clickjacking attack in the popup box, leaving the end-user with a miserable choice between forgoing the web-site, learning to use an ad-blocker and script-blocker, or clicking it out of the way and getting a virus.
A quick example of nuisance overlay popups: https://seekingalpha.com/news/3515622-diamondback-plunges-lower-oil-output-raises-well-spacing-concerns -- if you view the page while not logged in you get a popup that darkens the rest of the page and prompts you to get email alerts. I'm sure the rest of you have seen similar annoyances on other websites as well.
IMPORTANT NOTE: Nuisance in-page overlay popups are NOT the same as traditional pop-up ads, which open in a new window or tab. Overlay popups occur in the same tab or window as the content they are associated with.
I'm looking for an automated way to block them, preferably in tandem with disabling blurring and darkening CSS effects that are often abused to block the user's view pending some demand. Some quick insights on automated ways to detect overlay popups:
- Look for elements that hover or float in a fixed position over more than 90% of the page with a CSS descriptor designed to interfere with the end-user's viewing of the page (usually darken or blur). These are candidate nuisance in-page overlays.
- For each of these elements, scan them for an additional element that hovers or floats in the middle of the page, again in a fixed position. That's the nuisance prompt, demanding that you agree to something, log in, sign something, or whatever - and it could have a clickjacking attack or malware embedded. If such an element is found, remove the outer container (blur/darken element) found in the previous step from the page view.
