Amazon Alexa software version 8960323972 on Echo Dot 2nd generation and 3rd generation devices potentially allows attackers to deliver security-relevant commands via an audio signal between 16 and 22 kHz (often outside the range of human adult hearing). Commands at these frequencies are essentially never spoken by authorized actors, but a substantial fraction of the commands are successful.

Amazon Echo Dot devices through 2021-07-02 sometimes allow attackers, who have physical access to a device after a factory reset, to obtain sensitive information via a series of complex hardware and software attacks. NOTE: reportedly, there were vendor marketing statements about safely removing personal content via a factory reset. Also, the vendor has reportedly indicated that they are working on mitigations.

DISPUTED Prior to 2018-04-27, the reprompt feature in Amazon Echo devices could be misused by a custom Alexa skill. The reprompt feature is designed so that if Alexa does not receive an input within 8 seconds, the device can speak a reprompt, then wait an additional 8 seconds for input; if the user still does not respond, the microphone is then turned off. The vulnerability involves empty output-speech reprompts, custom wildcard ("gibberish") input slots, and logging of detected speech. If a maliciously designed skill is installed, an attacker could obtain transcripts of speech not intended for Alexa to process, but simply spoken within the device's hearing range. NOTE: The vendor states "Customer trust is important to us and we take security and privacy seriously. We have put mitigations in place for detecting this type of skill behavior and reject or suppress those skills when we do. Customers do not need to take any action for these mitigations to work."

Improper Neutralization of audio output from 3rd and 4th Generation Amazon Echo Dot devices allows arbitrary voice command execution on these devices via a malicious skill (in the case of remote attackers) or by pairing a malicious Bluetooth device (in the case of physically proximate attackers), aka an "Alexa versus Alexa (AvA)" attack.