New research released by MWR InfoSecurity reveals how attackers can compromise the Amazon Echo and turn it into a covert listening device, without affecting its overall functionality.

Found to be susceptible to a physical attack, which allows an attacker to gain a root shell on the Linux Operating Systems and install malware, the Amazon Echo would enable hackers to covertly monitor and listen in on users and steal private data without their permission or knowledge.

By removing the rubber base at the bottom of the Amazon Echo, the research team could access the 18 debug pads and directly boot into the firmware of the device, via an external SD card, and install persistent malware without leaving any physical evidence of tampering. This gained them remote root shell access and enabled them to access the "always listening" microphones.

[...] The vulnerability has been confirmed to affect the 2015 and 2016 editions of the device. The 2017 edition of the Amazon Echo is not vulnerable to this physical attack. The smaller Amazon Dot model also does not carry the vulnerability.

More technical details can be found here.