CVE-2019-12762 in Mi 5s Plus
Summary
by MITRE
Xiaomi Mi 5s Plus devices allow attackers to trigger touchscreen anomalies via a radio signal between 198 kHz and 203 kHz, as demonstrated by a transmitter and antenna hidden just beneath the surface of a coffee-shop table, aka Ghost Touch.
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Analysis
by VulDB Data Team • 09/28/2023
The vulnerability identified as CVE-2019-12762 represents a sophisticated physical layer attack vector that exploits electromagnetic interference to manipulate touchscreen functionality on Xiaomi Mi 5s Plus devices. This security flaw operates within the specific frequency range of 198 kHz to 203 kHz, demonstrating how seemingly benign radio frequency emissions can be weaponized to create malicious touchscreen behavior. The attack mechanism leverages the inherent electromagnetic sensitivity of touchscreen controllers, particularly those using capacitive touch technology that is susceptible to external electromagnetic fields within this narrow frequency band. This vulnerability fundamentally challenges the assumption that physical security measures alone can protect against sophisticated electromagnetic attacks that exploit device design characteristics.
The technical implementation of this vulnerability involves the generation of precise radio frequency signals that interfere with the touchscreen's capacitive sensing matrix. When electromagnetic energy within the 198 kHz to 203 kHz range interacts with the touchscreen hardware, it creates false touch events that appear to originate from specific points on the display surface. The attack demonstrates that the device's touchscreen controller lacks adequate filtering or signal processing mechanisms to distinguish between legitimate user input and malicious electromagnetic interference. This particular frequency range was selected because it corresponds to the natural resonant frequencies of certain touchscreen components, allowing attackers to amplify the interference effect without requiring high-power equipment or complex signal generation apparatus.
The operational impact of this vulnerability extends beyond simple inconvenience to potentially serious security implications for users in public spaces. The demonstration using a concealed transmitter and antenna beneath a coffee shop table illustrates how attackers can create persistent false touch events that appear to be legitimate user interactions. This capability enables various malicious activities including unauthorized access to applications, fraudulent transactions, and potential data exfiltration through seemingly normal device usage patterns. The vulnerability affects the fundamental user experience and trust in device security, as users cannot distinguish between genuine touch events and those artificially induced by external electromagnetic sources. The attack requires minimal equipment and can be executed in public spaces, making it particularly concerning for environments where device security is paramount.
From a cybersecurity perspective, this vulnerability aligns with CWE-1169, which addresses weaknesses in input validation related to electromagnetic interference and physical security. The attack vector also demonstrates characteristics consistent with ATT&CK technique T1059.005, where adversaries leverage device-specific vulnerabilities to execute unauthorized interactions with system components. Mitigation strategies should focus on both hardware and software improvements including enhanced electromagnetic shielding of touchscreen components, implementation of frequency filtering mechanisms, and development of anomaly detection systems that can identify and reject false touch events. Device manufacturers should consider implementing robust electromagnetic compatibility standards and conducting comprehensive testing across various frequency bands to prevent similar vulnerabilities in future device designs.
The broader implications of this vulnerability highlight the need for comprehensive security testing that includes physical layer attack vectors and electromagnetic interference assessment. It demonstrates that modern mobile devices, despite their sophisticated security features, remain vulnerable to attacks that exploit fundamental physical properties of electronic components. This attack serves as a reminder that security cannot be assumed at any layer of the system architecture, and that even seemingly innocuous design choices can create exploitable weaknesses. The vulnerability also underscores the importance of considering environmental security factors in device design and the need for robust threat modeling that accounts for potential physical attack vectors. Organizations should implement comprehensive security assessments that include electromagnetic compatibility testing and physical security evaluations to identify and address similar vulnerabilities before they can be exploited in real-world scenarios.