Banned Chrome AI Extension Returns with Malicious Update via Google CDN

A Chrome extension previously banned for stealing ChatGPT and DeepSeek conversation data has resurfaced on the Chrome Web Store and is now reaching enterprise endpoints through Google's own CRX distribution infrastructure, according to Netskope Threat Labs. The extension, advertised as "AI Sidebar with DeepSeek, ChatGPT, Claude and more," was flagged by OX Security in December 2025 for scraping user conversations and exfiltrating them to external domains. Before its removal in January 2026, it had amassed over 300,000 installs and a 4.6-star rating. After a months-long hiatus, the listing reappeared in August 2026, with Netskope confirming that enterprise browsers are once again receiving updates for the add-on.

The new payload, classified by Netskope as Trojan.GenericFCA.Script.37952, uses a calculated two-stage delivery strategy. Version 1.7.2.0, distributed between July 20 and July 31, 2026, shipped clean functionality to establish a trustworthy update history. Approximately two weeks later, version 1.7.3.0 introduced a surgical 21-line addition to a single script file that monetizes update and uninstall events. When Chrome reports an update event, a service worker opens an affiliate link in a new foreground tab. The link routes through a URL shortener to an AI video-generation platform running a public affiliate program, with code comments specifying that the trigger should fire on update rather than install, effectively turning every future release into a fresh commission. The uninstall path is equally opportunistic: operators exploit a Chrome quirk where only the most recently registered uninstall URL fires, overwriting the legitimate URL five seconds after it loads to ensure that users who remove the extension still generate a referral on the way out.

Attribution points to a company called Extchange.com, listed in the extension's own files as both developer and data controller. According to a WHOIS lookup, the domain was registered in February 2024 with no public registrant information, while the Chrome Web Store listing falsely shows the developer name as "DeepSeek AI." Netskope detected and blocked version 1.7.3.0 arriving at enterprise endpoints via Google's CDN and reported the extension to the Chrome Web Store before publishing its findings. The firm is advising organizations to remove the extension from managed devices immediately.

While Netskope frames the affiliate scheme itself as relatively low-stakes, the security researchers warned that the same update channel could just as easily carry a more damaging payload next time, given how cleanly the operators manipulated both Chrome's update events and the store's review process. For organizations reviewing their browser extension policies, running a privacy checkup on installed add-ons and inspecting service worker behavior with a browser fingerprint test can help surface unauthorized network activity before it reaches enterprise infrastructure.