Hardware Security

When a CPU hardware vulnerability is discovered, which is one countermeasure applied to CPUs already shipped?

  1. ARecalling all CPUs and replacing transistors one by one
  2. BUpdating the CPU microcode to change problematic internal behavior or add new controls the OS can use
  3. CChanging the marking on the CPU surface
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Answer: B. Updating the CPU microcode to change problematic internal behavior or add new controls the OS can use

Many CPUs implement complex instructions and some internal control in updatable microcode. When a vulnerability is found, the vendor distributes a microcode update loaded at every boot through the BIOS or OS. This can suppress problematic behavior or add new controls, such as instructions to flush branch predictors. Problems rooted in the circuitry itself are fixed fundamentally in the next CPU generation.

  • A. Transistors cannot be replaced.
  • B. Correct. It is combined with OS and compiler countermeasures.
  • C. Changing the marking does not change behavior.
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More Hardware Security questions

  1. Which best describes the problems addressed by hardware security?
  2. Which describes a side-channel attack?
  3. Which correctly pairs the principle behind timing attacks with a typical countermeasure?
  4. What weakness lurks in the password comparison function above, and what is the fix?
  5. What is the main reason cache-based side-channel attacks work?