Chrome Auto-Downloads 4GB AI Model Without Consent

Security researcher Alexander Hanff reported that Google Chrome automatically downloads a roughly 4GB AI model file onto users' devices without explicit consent or notification. The file, named weights.bin and part of Google's Gemini Nano on-device model, appears in a Chrome profile directory called OptGuideOnDeviceModel when the browser detects compatible hardware and active AI features, which are enabled by default in recent versions.

Hanff, who blogs as That Privacy Guy, first documented the behavior across Windows and macOS systems. The download, which can take about 15 minutes, supports local processing for features such as "Help me write" text assistance, scam detection, tab organization, and summarization APIs for websites. Users have noticed unexplained storage drops, particularly on devices with limited space like 256GB laptops. Deleting the file prompts Chrome to redownload it upon restart or next eligible opportunity, unless related features are disabled.

Google has acknowledged the model, stating it has offered Gemini Nano in Chrome since 2024 to power security tools like scam detection without sending data to the cloud. A company spokesperson noted that the model...