CIT 380: Securing Computer Systems

1. CIT 380: Securing Computer Systems Physical and EM Security CIT 380: Securing Computer Systems

2. Physical Security • Physical Security Plan • Elements of Physical Security • Environmental Threats • Physical Access • Theft • Backups • Printouts • Unattended Terminals • EM Security CIT 380: Securing Computer Systems

3. Physical Security Plan • List of physical assets to be protected • Descriptions • Replacement cost (hardware + data) • Locations of physical assets • Description of security perimeter(s) • Holes in perimeter (doors, windows, etc.) • Multiple perimeter example: • Outermost: campus • Outer: building • Inner: server room • Threats that you’re protecting against • Security defences CIT 380: Securing Computer Systems

4. Elements of Physical Security • Determent • Convince people not to attack. • Detection • Alarms, guards, and other means of detecting attacks. • Delay • Elements that slow down an attacker, e.g. locks & safes. • Response • Guards or a call to the police. CIT 380: Securing Computer Systems

5. Environmental Threats: Fire • Dangers: • Flames • Heat • Smoke • Water • Defences • Gas-charged extinguishers • Dry-pipe water sprinkler systems CIT 380: Securing Computer Systems

6. Environmental Threats: Temperature • Most computer systems need 50-90F • Dangers: • Cold: thermal shock on power-on, cracking ICs/boards. • Hot: unreliability, then system failures as heat increases. • Defences • Air-conditioning system • Good air circulation • Temperature alarm system CIT 380: Securing Computer Systems

7. Environmental Threats: Water • Humidity • Below 20% static discharge becomes a problem. • Must remain below dew point to avoid condensation on chilled surfaces. • Defences: • Humidifier/de-humidifier • Humidity alarm • Water • Defences: • Keep drinks away from computers. • Alarm at low level. • Automatic power shut-off at higher level. CIT 380: Securing Computer Systems

8. Environmental Threats: Electrical • Electrical Noise • Motors, fans, even vacuum cleaners can generate electrical surges. • Defences: • UPS with power line filter • Anti-static mats • Lightning • Defences • Turn off computer systems during lightning storms. • Surge suppressors may help for distant strikes. CIT 380: Securing Computer Systems

9. Environmental Threats • Dust • Collects on drive heads and degrades media by abrasion. • Dust is slightly conductive and can cause circuit boards to short and fail if much accumulates. • Defences: • Air Filtering Systems • Vacuuming • Vibration • Can work circuit boards out of sockets and drive heads out of alignment over time. • Defences: • Rubber or foam mat. CIT 380: Securing Computer Systems

10. Physical Access • Raised floors/dropped ceilings • If internal walls do not extend above dropped ceilings and below raised floors, computer room door security can be easily bypassed. • Air ducts • Serve computer room with many small air ducts. • Weld screens over air vents or within air ducts. • Motion detectors. • Glass walls • Easy to break—avoid them. CIT 380: Securing Computer Systems

11. Network Cabling • Threats • Wiretapping/monitoring • Cutting • Connecting to AC power • Defences • Run through steel conduits, not open trays. • Double-walled conduits with pressurized gas between layers; alarm if pressure falls. CIT 380: Securing Computer Systems

12. Alarms • Sensor types • Vibration detectors • Video cameras • Motion sensors • Infrared (body heat) detectors • False alarms • Causes • Weather (thunder, lightning, wind) • Created by attacker • Degrade response • guards/police will ignore alarms if too many false. CIT 380: Securing Computer Systems

13. Theft • Reasons: • Resale • Access to stored information • Targets • Laptops • Components: RAM, CPUs, hard disks • PCs/servers CIT 380: Securing Computer Systems

14. Theft Defences • Limit physical access. • Keep critical systems in high security areas. • Case locks to prevent access to components. • Laptop locks to lock laptop to desk. • Visible equipment tags with serial numbers. • Phone-home software for tracing. • Encryption of information. CIT 380: Securing Computer Systems

15. Backups • Protect availability of information. • Offer potential for confidentiality violation. • Defences: • Secure in safe after creation. • Periodically move to secure offsite storage. • Verify that you can restore data from backups. • Verify old backups periodically too. • Encrypt data on backup tapes. • Bulk erase tapes to destroy data before disposal. CIT 380: Securing Computer Systems

16. Printouts • Provide availability when computers down. • Potential for confidentiality violation. • Dumpster diving • Defences • Separate wastebaskets for confidential/unclassified information. • Paper shredding • Expensive shredding recovery services exist. CIT 380: Securing Computer Systems

17. Unattended Terminals • Offer anonymous attacker access • Defences: • Autologout shells or daemons • Automatic screen locking • Boot only from hard disk • BIOS password to protect boot settings • Case lock to prevent battery removal or BIOS chip replacement CIT 380: Securing Computer Systems

18. EM Security • What is EM Security? • History • Surveillance • Passive Attacks • Active Attacks • Defences CIT 380: Securing Computer Systems

19. EM Security Preventing a system from being attacked using electromagnetic emanations. • Confidentiality attacks • Listening to high frequency signals bled onto connected cables like power lines. • Listening to electromagnetic radiation leaked from computer devices. • Integrity attacks • Disrupting computations by inserting power glitches. • Availability attacks • Jamming, electromagnetic pulse weapons. CIT 380: Securing Computer Systems

20. History 1914: Telephone wires laid for miles parallel to enemy trenches only a few hundred meters away. Earth leakage caused crosstalk, allowing enemy to listen. 1960: UK listened to secondary signal on French embassy cable to capture plaintext leaked from cipher machine. 1960s: TV detector vans in UK listened to RF leakage to discover license fee evaders. 1985: Wim van Eck’s paper describing how to reconstruct picture on CRT at a distance. 1990s: Power analysis of smartcards. CIT 380: Securing Computer Systems

21. Active Surveillance • Many types of “bugs” available: • Battery-powered radio microphones. • Externally powered radio microphone/cameras. • Laser microphones Bounce laser off reflected surface, then measure modulation of reflected light by sound waves. • Interception evasion technologies • Rapid frequency hopping • Burst transmission CIT 380: Securing Computer Systems

22. Surveillance Countermeasures • Physical sweep • Nonlinear Junction Detectors • Emit weak radio signal. • Listen for harmonics caused by transistors. • Can find unshielded electronics a few feet away. • Surveillance receivers • Sweep radio spectrum at rapid rate, searching for unexplained signals. • Can detect frequency hoppers, but burst transmission difficult to find. CIT 380: Securing Computer Systems

23. Passive Attacks • Red/black separation • Power analysis • RF leakage CIT 380: Securing Computer Systems

24. Red/Black Separation • Red equipment: carries confidential data. • Black equipment: carries unclassified data. • Red/Black separation: Red equipment must be isolated from Black equipment by filters and shields. • Problem: Cipher machines have both red and black connections, so their design must be very careful. CIT 380: Securing Computer Systems

25. Power Analysis • Power analysis: analyzing power supply current of electronic device over time. • Transistor switching changes power draw. • Smartcards: credit-card sized plastic with embedded microprocessor/memory. • Uses: credit/ID card replacement, one time password authentication, physical access key. • Vulnerabilities • Low clock frequency compared to PCs. • Little or no power filtering. CIT 380: Securing Computer Systems

26. Power Analysis • Simple Power Analysis • Visual inspection of power consumption graph can reveal DES shifts and permutations or RSA multiplication and exponentiation operations. • Differential Power Analysis • Statistical analysis of many (100’s) operations where algorithm and either plaintext or ciphertext known. • Can be used to find 48 of 56 bits of DES key by analyzing last round of cipher. • Defences: randomization of order of S-box use, frequent key updates, timing randomness, insertion of random dummy operations. CIT 380: Securing Computer Systems

27. RF Leakage • All video displays (CRTs and LCDs) emit a weak TV signal. • All cabling (serial cables using by ATMs and ethernet cable used by PCs) emits signals too. • Keyboard RF emissions modulated by currently pressed key. • Defences: • Electromagnetic shielding of device or room. • Soft-Tempest fonts: low pass filter removes high frequencies of fonts—little visual difference on monitor but larger effect on signal. CIT 380: Securing Computer Systems

28. Active Attacks • Tempest Viruses • Glitching CIT 380: Securing Computer Systems

29. Tempest Viruses Malware that scans infected computer for desired information, which it then broadcasts via RF signals. • Change display when monitor not in use to send signal. • Superimpose signal on monitor image, so that image not visible on monitor but visible to RF receiver. CIT 380: Securing Computer Systems

30. Glitching • Inserting transients into power or clock signal to induce useful errors. • Example: On one Smartcard, replacing a clock pulse with two narrower pulses would cause processor to execute a NOP instead of scheduled instruction, allowing access control JMPs to be bypassed. CIT 380: Securing Computer Systems

31. Defences • Use Soft-Tempest fonts. • Keep cables short. • Use shielded cables. • Use EMI filters between PC and wall AC power. • Use EMI filters on fax/modem phone lines. • Apply ferrite core attenuators to cables. • Enclose devices in a Faraday cage (grounded tight cage of aluminum mesh.) • Buy specially shielded equipment. CIT 380: Securing Computer Systems

32. Key Points • Physical security is an essential component of computer security. • Many systems are more vulnerable to physical threats than system/network attacks. • Elements of Physical Security • Determent • Detection • Delay • Response • Backups are a defence against many threats, but must be defended themselves. CIT 380: Securing Computer Systems