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How to Build a Low-Cost, Extended-Range RFID Skimmer

How to Build a Low-Cost, Extended-Range RFID Skimmer. Ilan Kirschenbaum & Avishai Wool 15 th Usenix Security Symposium, 2006 * Presented by Justin Miller on 4/5/07. Overview. Background. RFID uses ISO-14443 standard Increased security Very short range (5-10cm) Goals

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How to Build a Low-Cost, Extended-Range RFID Skimmer

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  1. How to Build a Low-Cost, Extended-Range RFID Skimmer Ilan Kirschenbaum & Avishai Wool 15th Usenix Security Symposium, 2006 * Presented by Justin Miller on 4/5/07

  2. Overview

  3. Background • RFID uses ISO-14443 standard • Increased security • Very short range (5-10cm) • Goals • Build extended-range RFID skimmer • Collects mass info from RFID devices

  4. Outline • RFID • System design • Building • Tuning methods • Results • Conclusions

  5. RFID Technology • Many applications • Contactless credit-cards • National ID cards • E-passports • Other access cards • Very short range • Security vulnerabilities

  6. Attacks on RFID • Relay Attack

  7. Attacks on RFID • Relay Attack

  8. Attacks on RFID • German Hacker • PDA and RFID read/write device • Changed shampoo prices from $7 to $3 • Johns Hopkins Univ. • Sniffs info from RFID-based car keys • Purchased gasoline for free

  9. ISO-14443 • Proximity card used for identification • Very short range (5-10 cm) • Embedded microcontroller • Magnetic loop antenna (13.56 MHz) • Security • Cryptographically-signed file format

  10. RFID Skimmer • Collect info from RFID tags • Signal/query RFID tags close by • Record responses • Some uses: • Retrieve info from remote car keys • Obtain credit card numbers

  11. System Design Goals • Low power • Low noise • Large read range • Simple design • Cheap

  12. System Design

  13. Part #1 - RFID Reader • TI S4100 Multi-Function reader • Cost: $60 • Built in RF power amplifier • Sends approx. 200mW into small antenna

  14. Part #2 - RFID Antenna • Antenna range ≈ length • 39 cm copper tube loop • Antenna inductance ≈ 1 μH

  15. Part #3 - Power amplifier • Amplifier interfaced directly to module’s output stage • Powered by FET voltag • Field-effect transistor • Did not match impedances between amp and output

  16. Part #4 - Receiver Buffer • Load Modulation Receive Buffer • HF reader system • Receiver input directly connected to reader’s antenna • Attenuate signals before feeding them back to the TI module • Avoid potential reader damage • Still deliver input signals to receiver

  17. Part #5 - Power Supply • Powers the large loop antenna • Maintain “smooth” DC supply • Clean power supply • Low ripples (power variance) • Improves detection range

  18. System Building • Copper Tube Loop Antenna • Ideal: 40x40 cm • Copper-tube • Constructed their own • Cheaper copper tube, used for cooking gas • Pre-made in circular coils

  19. System Building • Copper-tube loop and PCB antennas

  20. System Building • RFID Base Board • Decon DALO 33 Blue PC Etch pen • Protected ink used to draw leads on tablet

  21. System Building • RFID Base Board and power amp

  22. System Building • Power Amplifier • Based on Melexis application note • Input driven from reader output • Ideal: high voltage rating capacitors • Used cheaper, but low voltage

  23. System Building • Load Modulation Receive Path Buffer • Signals are looped back • Buffer needed to hold correct signals

  24. System Tuning • RF Network Analyzer • Measure magnitude and phase of input • Measure Voltage Standing Wave Radio • Adjust antenna’s impedance to match amplifier output • RF power meter • Measures power reception • Ideal: measure actual amplification

  25. Experiment Notes • Power supply affects skimmer mobility • Clean increases RFID detection range • System tuning finds maximal power transfer between circuits

  26. Results • Increased RFID Scan Ranges • 12-V battery • 16.9 cm (PCB), 23.2 cm (copper tube) • With power amp • 17.3 cm (PCB), 25.2 cm (copper tube)

  27. Results

  28. Results • Close to theoretical predictions

  29. Contributions • Built RFID skimmer  validated basic concept of an RFID “Leech” • RFID tags can be read from greater distances (25 cm) • Halfway towards full implementation of a relay-attack

  30. Strengths • Created a portable, RFID skimmer • Step-by-step instructions • Low system cost ($60)

  31. Weaknesses • Not developed for large scale production • Cheap design = less efficient results • Expensive system tuning methods

  32. Improvements • Better equipment • Use copper-tube loop antenna • Power amp with higher voltage rating capacitors • RF Tuning: measure actual amplification instead of power • High rating components • More powerful RF test equipment

  33. Questions? • Ask me!

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