CVE-2023-33248 in Alexa
Summary
by MITRE • 05/25/2023
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.
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Analysis
by VulDB Data Team • 01/03/2026
The vulnerability described in CVE-2023-33248 represents a significant audio-based attack vector targeting Amazon Alexa devices, specifically affecting Echo Dot 2nd and 3rd generation models running software version 8960323972. This flaw exploits the natural audio processing capabilities of voice assistants by leveraging ultrasonic frequencies within the 16 to 22 kilohertz range, which operate outside the typical hearing spectrum of most adults while remaining within the operational range of many consumer audio systems. The attack methodology capitalizes on the fact that these devices continuously listen for wake words and process audio signals, creating an exploitable window where malicious actors can transmit commands without human vocalization.
The technical implementation of this vulnerability stems from insufficient audio filtering mechanisms within the Alexa software stack, particularly in how the system processes and validates incoming audio signals. The flaw allows attackers to bypass normal authentication and authorization protocols by transmitting commands through ultrasonic frequencies that are typically filtered out or ignored by standard audio processing algorithms. This creates a persistent threat vector where commands can be issued without the need for physical access or traditional network-based attacks, as the malicious audio signals can be transmitted through speakers or other audio output devices that can reproduce these frequencies. The vulnerability specifically targets the device's speech recognition engine and command processing pipeline, where the system fails to properly distinguish between legitimate human speech and artificially generated ultrasonic commands.
The operational impact of this vulnerability extends beyond simple unauthorized command execution, as it represents a sophisticated attack vector that can be leveraged for various malicious activities including unauthorized device control, data exfiltration, and potential privacy violations. Attackers can potentially issue commands that trigger device functionality such as playing music, making calls, accessing connected smart home systems, or even initiating network communications that could lead to broader security compromises. The fact that a substantial fraction of these ultrasonic commands are successful indicates that the attack has high reliability, making it particularly concerning for consumer privacy and security. The vulnerability also demonstrates the challenges in securing IoT devices that operate in uncontrolled acoustic environments where malicious actors can potentially exploit audio transmission capabilities without detection.
Mitigation strategies for this vulnerability should address both the software and operational aspects of the attack surface. The most effective approach involves implementing enhanced audio signal filtering mechanisms that specifically target and block ultrasonic frequency ranges while maintaining normal device functionality. This aligns with common security practices outlined in the CWE database, particularly CWE-200 for information exposure and CWE-310 for cryptographic issues, though the specific implementation focuses on audio signal processing rather than traditional cryptographic vulnerabilities. Device manufacturers should also consider implementing frequency-based signal validation that can detect anomalous audio patterns indicative of automated command injection attempts. Additionally, the implementation of behavioral analytics that can identify unusual command sequences or timing patterns can provide an additional layer of defense against this type of attack. Network-level mitigations such as firewalls and intrusion detection systems can also help detect and block suspicious traffic patterns that may indicate exploitation attempts, though these are secondary to the core audio processing fixes required to address the fundamental vulnerability. The attack surface described in this vulnerability aligns with several MITRE ATT&CK framework techniques including T1059.001 for command and scripting interpreter and T1566.001 for spearphishing attachment, though the specific execution method through ultrasonic audio represents a novel and concerning attack vector that requires specialized defensive measures.