If Brandy’s major concern is a compromised operating system, she can bypass the operating system on the device by booting it from live boot media and running her own operating system on the hardware. Running a malware scan may provide her with some information but may not detect all compromises and Brandy likely does not have the necessary permissions to correct any issues. Using a VPN or accessing secure sites would not protect her against a compromised operating system, as the operating system would be able to view the contents of her communication prior to encryption.