Siri and Alexa can be turned against you by ultrasound whispers

You might not have, but Alexa did. Voice assistants have been successfully hijacked using sounds above the range of human hearing. Once in, hackers were able to make phone calls, post on social media and disconnect wireless services, among other things. Assistants falling for the ploy included Amazon Alexa, Apple's Siri, Google Now, Samsung S Voice, Microsoft Cortana and Huawei HiVoice, as well as some voice control systems used in cars. The hack was created by Guoming Zhang, Chen Yan and their team at Zhejiang University in China.