Security researchers have confirmed that MacBook webcams can spy on their users without the warning light being activated.
Apple computers have a “hardware interlock” between the camera and the light that is supposed to ensure the camera can't be activated without alerting the user by lighting a tell-tale LED above the screen
However Stephen Checkoway, a computer science professor at Johns Hopkins University and graduate student Matthew Brocker were able to circumvent this security feature by reprogramming the micro-controller chip inside the camera.
Normally, any program running on a MacBook’s central processing unit that takes images through Apple's iSight camera would turn on the tell-tale light. Brocker and Checkoway's reprogramming tactic allows the camera and it light to be activated independently, so that the camera can be running while the light is switched off.
The researchers have released proof-of-concept software to demonstrate the trick, including a paper , entitled iSeeYou: Disabling the MacBook Webcam IndicatorLED. The study provides the first public confirmation that a sophisticated hacker tactic long suspected to be part of the playbook of intelligence agencies, feds and others is not only possible but relatively straightforward.
The same technique that allows us to disable the LED, namely reprogramming the firmware that runs on the iSight, enables a virtual machine escape whereby malware running inside a virtual machine reprograms the camera to act as a USB Human Interface Device (HID) keyboard which executes code in the host operating system. We build two proofs-of-concept: (1) an OS X application, iSeeYou, which demonstrates capturing video with the LED disabled; and (2) a virtual machine escape that launches Terminal.app and runs shell commands. To defend against these and related threats, we build an OS X kernel extension, iSightDefender, which prohibits the modification of the iSight’s firmware from user space.
Privacy conscious users have one ready means to protect themselves from spying. “The safest thing to do is to put a piece of tape on your camera,” Miller told the Washington Post.
A video demonstrating how the iSight camera can be turned on without activating the small-green LED light on older Macs can be found here.