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Emission Security

Emission Security. Kay Jr-Hui Jeng. Emission Security (Emsec). Refers to preventing a system from being attacked using compromising emanations. How important is it. Military Organizations Spent as much on it as on cryptography Commercial World

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Emission Security

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  1. Emission Security Kay Jr-Hui Jeng

  2. Emission Security (Emsec) • Refers to preventing a system from being attacked using compromising emanations

  3. How important is it • Military Organizations • Spent as much on it as on cryptography • Commercial World • The uptake of smartcards was materially set back in the last few years

  4. History of Emsec • “Crosstalk” between telephone wires (1914) • Field telephone wires using single-core insulated cable • Earth Leakage caused crosstalk including messages from enemy side. • The tempest attacks were not just feasible, but could be mounted with simple equipment (1985)

  5. History of Emsec (cont’d) • Smart cards • Broken by inserting transients. Or glitches in power or clock lines (1996). • Crypto keys used in smart cards could be recovered by appropriate processing of precise measurements of the current drawn by the card (1998).

  6. Common Emsec attacks • Most attacks are not those that exploit some unintended design feature of innocuous equipment, but those in which a custom-designed device is introduced by the attacker. • If information can be captured by a device, then no subsequent protective measures are likely to help very much.

  7. Emsec attack devices • Simple radio microphone • Radio transmitter & TV camera • Exotic device • A wooded replica of the Great Seal of the U.S was presented to U.S. ambassador in Moscow in 1946 • In 1952, it was discovered to contain a resonant cavity that acted as a microphone when illuminated by microwaves from outside the building, and retransmitted the conversations in the office.

  8. Emsec attack devices (cont’d) • Laser microphones • Work by shining a laser beam at a reflective in the room where the target conversation is taking place. • The sound waves modulate the reflected light, which can be picked up and decoded at a distance. • High-end devices • Used today by governments • Low-probability-of-intercept radio techniques

  9. Types of Emsec attack • Passive attacks • the opponent makes use of whatever electromagnetic signals are presented to him without any effort. • Electromagnetic eavesdropping • Active attacks • Disruptive electromagnetic attacks

  10. Passive attacks • Leakage through power and signal cables • Exploited for military purposes since in 1914. • Conducted leakage of information can be largely suppressed by careful design with power supplies and signal cables.

  11. Passive attacks (cont’d) • Leakage through RF signals • Early IBM machine with a 1.5MHz clock & Radio Tuned to this frequency emits a loud whistle • Video display units emit a weak TV signal • A VHF/UHF radio signal, modulated with a distorted version of the image currently being displayed • LCD displays are also easy for the eavesdropper

  12. Active attacks • Tempest viruses • Nonstop • Glitching • Differential fault analysis • Combination attacks • Commercial exploitation

  13. Active attacks (cont’d) • Tempest viruses • Infect a target computer and transmit the secret data to a radio receiver hidden nearby. • Nonstop • Nonstop is the exploitation of RF emanations that are accidentally induced by nearby radio transmitters and other RF sources.

  14. Active attacks (cont’d) • Glitching • By changing power & clock signals attacker can step over jump instructions & force resets

  15. Active attacks (cont’d) • Differential fault analysis • S = Md (mod p*q) • If card returns defective signature (Sp) which is correct modulo p but incorrect modulo q then we have: • p = gcd (p*q, Spe– M)  Breaks System

  16. Active attacks (cont’d) • Combination attacks • Use a combination of active and passive methods. • If PIN was incorrect, they would decrement a retry counter writing to EEPROM. • The current consumed by the card rose were charge up. • The attacker could simply reset the card and try the next candidate PIN. • Commercial exploitation • SFX Entertainment monitors what customers are playing on their car radios by picking up the stray RF from the radio’s local oscillator.

  17. Emsec protection devices • Nonlinear junction detector • A device that can find hidden electronic equipment at close range. • Surveillance receiver • The better ones sweep the radio spectrum from 10 KHz to 3 GHz every few tens of seconds, and look for signals that can’t be explained as broadcast, police, air traffic control and so on.

  18. Emsec protection devices (cont’d) • Electromagnetic Shielding • Double pane windows to prevent laser microphones • Some facilities at military organizations are place in completely shielded buildings or underground.

  19. Conclusion • Although originally a concern in the national intelligence community, Emsec is now a real issue for companies that build security products such as smart cards and cash machines.

  20. References • Ross Anderson, “Security Engineering”, pp.305-320 • http://www.tpub.com/content/USMC/mcr3403b/css/mcr3403b_79.htm • http://isis.poly.edu/courses/cs996-management/ Lectures/Transec-Emsec-Tempest.ppt

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