Google Chrome is preparing to implement a new security feature designed to block extensions that hijack the New Tab page or alter the default search engine, particularly on unmanaged consumer devices. This protection aims to counteract a common abuse where malicious programs exploit Chrome's enterprise policy features to force-install unwanted extensions.
The upcoming change, identified in ongoing Chromium Gerrit development, is not yet active but is planned for default enablement once approved. Anunoy Ghosh, a Google developer, noted that in "low-trust environments" like unmanaged consumer PCs, enterprise policy force-installs are often misused to lock in search engine or New Tab page hijackers.
Currently, Chrome permits organizations to use enterprise policies to force-install extensions and manage browser settings. While this functionality is legitimate for properly managed work devices connected to a domain or mobile device management (MDM) system, malware has been exploiting it on personal computers. Malicious software can add local Chrome policy keys without user consent, leading to the forced installation of extensions that replace the New Tab page, change the default search engine, or redirect searches to suspicious websites.
In such scenarios, Chrome may interpret these extensions as administrator-installed, preventing users from removing or disabling them. Users might also encounter a "Managed by your organization" message, even if their PC is not actually owned or managed by an organization. Google defines these consumer PCs as low-trust environments because Chrome processes locally stored policies without verification from a trusted authority like a domain or MDM service.
Under the proposed security measure, Chrome would block attempts to install policy-controlled extensions that override the New Tab page or default search engine. The installation would be canceled, and the extension ID would be saved in a blocked-extension preference. Chrome would also cease attempting to download the blocked extension during subsequent policy checks, thereby preventing repeated installation attempts and unnecessary network activity.
Google is also addressing another tactic used by malware: preventing manually installed extensions from being converted into locked, policy-controlled extensions. Such extensions would remain under user control, allowing for their disablement or removal. Furthermore, if a previously managed device loses its trusted management status but retains local policy keys, Chrome would automatically uninstall any affected New Tab or search-engine override extensions.
The company plans to incorporate metrics to monitor the prevalence of these policy-based hijackers and the frequency with which Chrome blocks them. For legitimate administrators, an "escape-hatch" policy will be available to disable the protection if a required enterprise extension legitimately overrides the New Tab page or search engine. The Gerrit changes are still under review, meaning the feature is not yet available in the stable version of Chrome.
