Beware of this Chrome extension: it spies on searches by pretending to be Perplexity AI

Microsoft has discovered a Chrome extension that masqueraded as Perplexity AI and secretly intercepted users' searches, redirecting them to servers controlled by the attackers before returning the real results. The chosen name, "Search for perplexity ai," sounded credible enough to deceive those searching for the homonymous AI-based search engine. Google has removed it from the Chrome Web Store after the report, but those who have already installed it must uninstall it manually.

The Microsoft Threat Intelligence team reconstructed the mechanism in a post published earlier this week. The extension, which had reached version 2.2 and was built on Manifest V3, requested permissions much broader than necessary for a simple additional search engine.

A hijacking disguised as a normal search

The key to the deception lay in the "chrome_settings_overrides" function, which was used to set itself as the default search engine of the browser. From that moment on, every query typed in the omnibox was routed to perplexity-ai.online, a "typosquatted" domain (which exploits a typo or similarity to a real domain) designed to resemble the legitimate perplexity.ai, before being forwarded to the actual results.

The interception was handled by the declarativeNetRequest permissions, which allowed the extension to monitor and modify network traffic in real-time, including suggestion boxes while the user was typing. Microsoft identified a Node.js server behind the bogus domain that recorded every incoming request, method, URL, and complete HTTP header, along with an nginx configuration with a Let's Encrypt SSL certificate designed to make the connection appear secure.

There are no traces of password or login credential theft. The risk instead concerns profiling: with weeks of intercepted queries, those managing the infrastructure could accurately reconstruct the interests and online habits of each user, data that lends itself to uses ranging from targeted advertising to more opaque scenarios.

For those wishing to check if their browser is involved, Microsoft has published the unique identifier of the extension, flkebkiofojicogddingbdmcmkpbplcd, which is useful for tracking it down even if the displayed name changes.

Removing it takes a few steps: open chrome://extensions/, enable developer mode in the top right, search for the extension by that ID, and click Remove. It's also worth checking the default search engine settings, as a manual reset may be necessary even after uninstallation.

This episode confirms that the checks of the Chrome Web Store, despite improvements over the years, remain bypassable by those who know how to build a credible clone of a popular service. Microsoft advises periodically reviewing installed extensions, being wary of permissions that are too broad relative to the stated function, and always preferring verified developers, especially for tools related to artificial intelligence, which today are among the preferred targets of those seeking to intercept large amounts of browsing data.