Chrome Store Hosts 'Poper Blocker' Spyware Downloaded by Millions

A purported ad-blocker exfiltrates reams of sensitive information, and benefits from having Google's stamp of approval despite researcher warnings.

Millions of people have downloaded infostealers disguised as legitimate ad-blocking browser extensions, in part because Google has provided them with seals of approval on the Chrome Web Store.

That's the word from Bay Area Labs, which uncovered "Poper Blocker" lurking in the Chrome Web Store. It has every trapping of a legitimate, mainstream app: it sports a big, green "Featured" badge, and its developer has earned a trustworthy "Established Publisher" status with Google. It enjoys a 4.8 out of 5 star rating from more than 81,000 reviewers. It claims more than 2 million active users. In short, no user could spot anything untoward this program, were they to come across it while shopping for an ad blocker.

Yet Poper Blocker is malware, plain and simple, according to researchers at Bay Area Labs. They have found evidence that it exfiltrates inordinate amounts of sensitive data from its users, including detailed browser histories, screengrabs, and AI chatbot interactions. To facilitate its data theft, it uses classic malware techniques like code obfuscation and sandbox detection, they tell Dark Reading.

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What's worse, though, is that Poper Blocker isn't alone. In researching this story, Dark Reading identified two other popular apps from the same developer which are also "featured" on the Chrome Web Store, despite having been identified as spyware nearly a decade ago.

In May 2026, Bay Area Labs reported Poper Blocker to Google, but researchers say to no effect. For its part, Google didn't immediately respond to Dark Reading's request for on this story.

Ad blockers need to know what websites you visit, so they can perform their stated function — but they don't need to record and exfiltrate that data.

Yet Poper Blocker records the full, unabridged URL for every single page its users visit, according to Bay Area Labs' findings, which it shared exclusively with Dark Reading. The program can also screenshot and scrape data from those pages. And, it records Claude, ChatGPT, and Gemini chat histories; this data includes not only the prompts that users type, and the answers they receive back, but also oddly granular information, like titles of conversations, records of models' thought processes , which model users used, and what subscription tier they pay for.

The app also identifies users' approximate locations, and assigns them cross-device IDs, so that if they use Poper Blocker on multiple devices, all of that data will be associated with the same individual.

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With regard to browsing data, for instance, the vendor acknowledges that its extensive collection will inevitably catch "information that may contain what would be considered sensitive information," and that that in certain cases its affiliates "may disclose this information to their customers so that their customers can analyze this information for market research purposes or consumer behaviors."

Users who wish to opt out of third-party data sharing receive a popup on every single page they visit, warning that "advanced [ad] blocking features won't activate" until they comply. The toggle to opt out anyway counterintuitively turns green when users opt in — a known deceptive design pattern, Bay Area Labs points out.

Source: Bay Area Labs

Taking a page from modern malware best practices, Poper Blocker keeps its malicious functionality outside of its primary codebase. Instead, it ships an interpreter, which downloads and interprets instructions from a command-and-control (C2) server. To avoid detection by Google reviewers and cybersecurity researchers, it waits idle for 24 hours upon installation before running any malicious functions. It persists, even though Google banned this behavior in its latest rulebook for browser extensions, Manifest V3 (MV3).

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To further frustrate analysts, Poper Blocker both encodes and obfuscates its payloads . Even if researchers manage to untangle the mess, it refers to its commands using numbers instead of names, and the numbers can only be interpreted using a dictionary from the attacker-controlled C2 server. The app also runs checks to identify whether it's in a sandbox, and it can change its C2 domain at any time.

Spyware Vendor Flies Under the Radar

In 2018, the ad-blocking company AdGuard identified seven mobile and browser apps that performed malicious data theft, all developed by a company called " Big Star Labs ." At the time, the seven apps enjoyed more than 11 million cumulative users.

Not all of those apps appear to have survived the years since, but at least three — Poper Blocker, "CrxMouse," and "BlockSite" — remain live on the Chrome Web Store today. In combination, they serve nearly four million users from the Chrome Web Store. BlockSite has also been downloaded more than 10 million times on Google Play.

Dark Reading independently investigated Big Star Labs. The company appears to have been founded in 2010, at a WeWork coworking location in central London, according to . Its lists three employees, but each of those employees' profiles uses a free stock photo as its profile picture. One of these fake profiles lists a data-mining startup as a prior employer.

In 2017, the company registered as a limited partnership in Delaware, where companies are not required to identify their owners and operators in public documentation. The company listed its address as an unmarked, one-story building behind a Dollar Tree in a small Delaware town. The address is shared with a variety of other shell companies.

Google is aware of claims around Big Star Labs. Google removed its apps from the Chrome Web Store the day after it was outed by AdGuard, eight years ago. Two weeks afterwards, however, some of those apps were reinstated.

Dark Reading also contacted Big Star Labs for on this story. It has not responded as of press time. Every Big Star Labs browser extension today sports an "Established Publisher" badge, indicating that Google established the publisher's identity and awarded its "consistent positive track record" in complying with Google's policies.

Cybersecurity Tools Won't Save You

Big Star Labs isn't the only accredited vendor distributing spyware on mainstream app stores. In automated tests, Bay Area Labs found that one in every five ad blockers with more than 100,000 users exfiltrated users' browser histories in some form or another. Bay Area Labs showed Dark Reading a list of high-profile offenders, including one app with more than 3 million users (Dark Reading has chosen to withhold the names of these suspect apps, as Bay Area Labs has not yet been able to manually double check all of its findings).

Many naughty ad blockers present like Poper Blocker — that is to say, they provide the public with no visible clues that they monetize user data. Short of wading through long privacy policies, individuals have no way of distinguishing malicious ad blockers from legitimate ones.

Organizations might assume that their cybersecurity software would prevent unauthorized data egress. Bay Area Labs founder James Arnott pours water on that idea. As just one example, he says, "A DLP [data loss prevention] might flag and block a suspicious request [to exfiltrate sensitive data]. It might have a regex to match data patterns . With Poper Blocker, this won't apply because they've used this obfuscation."

He adds, "Unless you manually look into it, and you know what you're doing, and you know how to obfuscate the data that's sent off, it's pretty much impossible to detect."

Nate Nelson is a journalist and award-winning scriptwriter. In addition to Dark Reading he writes for Darknet Diaries, the most popular show in cybersecurity across all media.

He began his career as a freelancer, ghostwriting Forbes and CNBC op-eds for executives in tech and finance. Then he transitioned to journalism at Threatpost, where he covered cybersecurity news and trends. Throughout those years he co-created a cybersecurity podcast, Malicious Life, which in its day climbed into the Top 20 technology podcasts charts on Apple Podcasts and Spotify.

He holds degrees from New York University and Bard College. As a born and bred New Yorker, he enjoys a superiority complex, but is polite enough to keep it to himself.

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