Tal Be’ery and Amichai Shulman found that the always-listening Cortana agent responds to some voice commands even when computers are asleep and locked, allowing someone with physical access to plug a USB with a network adapter into the computer, then verbally instruct Cortana to launch the computer’s browser and go to a web address that does not use https—that is, a web address that does not encrypt traffic between a user’s machine and the website. The attacker’s malicious network adapter then intercepts the web session to send the computer to a malicious site instead, where malware downloads to the machine, all while the computer owner believes his or her machine is protected.

Source: Researchers Bypassed Windows Password Locks With Cortana Voice Commands – Motherboard