> Why aren‘t physically-local attacks in Chrome’s threat model?
> We consider these attacks outside Chrome's threat model, because there is no way for Chrome (or any application) to defend against a malicious user who has managed to log into your device as you, or who can run software with the privileges of your operating system user account. Such an attacker can modify executables and DLLs, change environment variables like PATH, change configuration files, read any data your user account owns, email it to themselves, and so on. Such an attacker has total control over your device, and nothing Chrome can do would provide a serious guarantee of defense. This problem is not special to Chrome — all applications must trust the physically-local user.
https://chromium.googlesource.com/chromium/src/+/master/docs...