ReThink: Revealing Electromagnetic Interference Threats to Power Inverters at NDSS 2025

Introduction to Power Inverters

• 💡 Power inverters are essential for converting DC power from renewable energy sources into AC power for the grid, playing a critical role in stable energy operation.
• ⚠️ A slight frequency drop (e.g., two hertz) in DC power can lead to grid shutdowns and localized power blackouts.
• 🎯 The research explores electromagnetic interference (EMI) attacks on these inverters, aiming to cause shutdowns, power reduction, or physical damage without direct contact.

The Threat of EMI Attacks

• 🧠 Power inverters rely on voltage and current sensors for their two-stage conversion process (DC-DC and DC-AC).
• ⚡ These internal sensors are vulnerable to electromagnetic interference (EMI) at 1 GHz or higher, even with existing electromagnetic compatibility (EMC) countermeasures.
• 📉 Such EMI can cause incorrect measurements, deceiving control algorithms and creating an emerging Cyber-Physical attack surface for future grids.

How EMI Affects Sensors

• 🔬 Injected AC noise from EMI is converted into a DC offset on sensors by operational amplifiers rectifying and amplifying the signal.
• ➕➖ The resulting offset can be both positive or negative due to differing coupling frequencies on the two inputs of the differential amplifier.
• 🛠️ Amplitude modulation is identified as a method to achieve controllable manipulation of sensor readings.

ReThink Attack Methodologies

• 🚫 Denial of Service (DoS) attacks are achieved by inducing sudden changes in sensor readings to trigger protection mechanisms on both DC and AC sides.
• 🔥 Damage attacks subtly manipulate sensor readings to be lower than the real voltage, causing the actual voltage to gradually increase and eventually burn out the inverter.
• 📊 Damping attacks inject specific frequencies to create noise, preventing the optimization algorithms from converging to the optimal power output.

Real-World Validation & Countermeasures

• ✅ The ReThink attacks were successfully validated on five off-the-shelf PV inverters and a simulated real-world 400 kW microgrid.
• 🚀 Attacks were demonstrated effective from a distance of 100-150 cm with a total power of under 20W.
• 🛡️ Proposed countermeasures include hardware modifications, shielding, and detection mechanisms to mitigate these EMI threats.