Two million people installed this ad blocker. It reads their AI chats.

Two million people use a pop-up blocker called Poper Blocker. It has 4.8 stars from 81,600 ratings, a Featured badge from Google and a verified publisher mark. On 28 September a researcher named James Arnott published a teardown of what it does once installed.

His finding is that the extension does not ship its data-collection logic in the code Google reviews. It downloads the instructions from its publisher's servers afterwards, so what gets harvested can be changed at any time without an update. What it was harvesting when he looked: your full browsing history with URLs and referrers, your activity on Facebook, Instagram, LinkedIn and X, a browser fingerprint, identifiers synced across your devices, and your conversations with ChatGPT, Claude and Gemini. It waits roughly 24 hours before delivering the interesting parts, which is long enough to sail past an automated review. Even leaving leaks something: the uninstall URL carries your last five domains with it.

Arnott says Google was told about the AI chat scraping back in May. The listing is still live this weekend, still showing 4.8 stars and around two million users. In August we covered a different extension doing much the same thing, which had 300,000 users and had already been thrown off the store once.

The lesson is not to avoid extensions, it is to audit the ones you already have. Open your browser's extensions page, remove anything you do not actively use, and read the store badges as marketing rather than a safety check. Tendvane's browser hijacked repair wizard goes over the same ground when a browser has started behaving strangely and you want to see what has been bolted onto it.