CVE-2018-20823 in Mi 5s
Summary
by MITRE
The gyroscope on Xiaomi Mi 5s devices allows attackers to cause a denial of service (resonance and false data) via a 20.4 kHz audio signal, aka a MEMS ultrasound attack.
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Analysis
by VulDB Data Team • 09/07/2023
The vulnerability identified as CVE-2018-20823 represents a critical security flaw in the gyroscope hardware of Xiaomi Mi 5s mobile devices that enables attackers to execute denial of service attacks through specifically crafted audio signals. This vulnerability exploits the physical characteristics of MEMS (Micro-Electro-Mechanical Systems) sensors that are commonly integrated into mobile devices for motion detection and orientation tracking. The gyroscope sensor in these devices operates within a specific frequency range and exhibits resonance characteristics that can be manipulated through external acoustic stimuli.
The technical exploitation of this vulnerability occurs when attackers transmit a 20.4 kHz audio signal that matches the resonant frequency of the gyroscope sensor. This specific frequency creates mechanical vibrations that interfere with the normal operation of the sensor, causing it to generate false data readings and potentially triggering system instability. The attack leverages the inherent physical properties of the MEMS gyroscope, which functions as a micro-mechanical device with moving parts that can be influenced by acoustic energy at certain frequencies. This type of attack falls under the category of physical layer attacks that target hardware components rather than software vulnerabilities.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the false data generated by the compromised gyroscope can affect various system functionalities that depend on accurate orientation and motion data. Mobile applications that utilize gyroscope data for navigation, gaming, augmented reality experiences, and security features such as face recognition or motion-based authentication mechanisms may experience degraded performance or complete failure. The vulnerability demonstrates how physical hardware components can become attack vectors when their operational characteristics are not properly accounted for in security design considerations. This attack represents a sophisticated approach to compromising mobile device functionality through acoustic interference rather than traditional digital attack methods.
Mitigation strategies for this vulnerability require both hardware and software approaches to address the fundamental design flaw in the gyroscope sensor implementation. Device manufacturers should implement frequency filtering mechanisms to prevent resonant frequencies from affecting sensor operation, while also considering the integration of anti-vibration measures in device design. Software-level mitigations include implementing data validation routines that can detect anomalous sensor readings and alert system components to potential interference. The vulnerability aligns with CWE-119 which addresses improper restriction of operations within a limited error handling scope and represents a specific instance of the broader category of physical security vulnerabilities that can affect embedded systems. Organizations should also consider implementing monitoring solutions that can detect unusual sensor behavior patterns that might indicate acoustic attack attempts. This vulnerability highlights the importance of considering physical attack surfaces during security assessments and aligns with ATT&CK technique T1583 which covers acquisition of infrastructure and T1499 which addresses network denial of service attacks through physical means.