Signal Injection Attack using Photoacoustics and its Countermeasure

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K11884
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 60070:Information security-related
• Research Institution: The University of Electro-Communications
• Principal Investigator: Sugawara Takeshi 電気通信大学, 大学院情報理工学研究科, 准教授 (60785236)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: セキュリティ

Outline of Final Research Achievements

The main physical mechanisms of Light Commands are identified as (i) thermoelastic bending, (ii) the thermal piston effect, and (iii) the photoelectric effect. We designed an experimental method for finding the contribution of each effects, and evaluated eight commercial MEMS microphones. First, any of the three types of effects can cause the Light Command vulnerability. Second, the internal structure and manufacturing process impact microphones’ light sensitivity, and we observed significant differences between the target microphones. Based on these results, we suggested countermeasures and discussed the possibility of similar attacks in other sensors.

Free Research Field

Security

Academic Significance and Societal Importance of the Research Achievements

本研究は，遠隔にいる攻撃者が，音声アシスタントに無音で音声コマンドを挿入する攻撃（ライトコマンド）に関するものである．この脆弱性は，MEMSマイクが意図せず光に感度を持つことによって生じる．本研究成果は，光が振動に変換される物理メカニズムを明らかにした．本成果は，ライトコマンドへの対策構築に必要な基礎を与える．また，同じメカニズムにより脆弱になりうるセンサを先回りして検出することができるようになる．