Measured Boot is a security feature that provides a trusted and verifiable boot process in modern computer systems. It is a key component of the Unified Extensible Firmware Interface (UEFI) boot security, designed to detect and prevent tampering or unauthorized changes in the boot process. Measured Boot works by creating a "Measured Boot Log" or "Event Log" that records cryptographic measurements of each step of the boot process. Here's how Measured Boot enhances system security:
1. Measuring Each Boot Component: During the boot process, each firmware, bootloader, and operating system component is cryptographically measured using a hash function. These measurements generate a unique cryptographic hash value for each component.
2. Storing Measurements in the Event Log: The cryptographic measurements are stored in a secure log called the "Measured Boot Log" or "Event Log." This log forms a chain of trust that starts from a trusted root and extends up to the operating system. The integrity of this log is critical for detecting any tampering attempts.
3. Establishing a Chain of Trust: Each measurement in the log is cryptographically linked to the previous one, creating a chain of trust. If any component in the boot process is modified or replaced, the chain of trust is broken, indicating a potential security breach.
4. Early Detection of Security Breaches: Measured Boot enables early detection of potential security breaches because any unauthorized changes in the boot process are immediately detectable through the Measured Boot Log.
1. Enhanced Boot Integrity: Measured Boot provides a strong foundation for booting the system securely, ensuring that only verified and trusted components are executed during the boot process.
2. Early Threat Detection: The cryptographic measurements in the Measured Boot Log allow for early detection of firmware-level attacks, rootkits, and other attempts to compromise the system's boot process.
3. Chain of Trust: The chain of trust established by Measured Boot helps ensure that the system boots from a known, trusted state, reducing the risk of unauthorized modifications.
4. Supporting Trustworthy Computing: By verifying the integrity of the boot process, Measured Boot contributes to creating a trustworthy computing environment.
Measured Boot is a critical security feature in modern computer systems, particularly those using UEFI firmware. By measuring and recording cryptographic values of each boot component, Measured Boot establishes a chain of trust that enables early detection of potential security breaches during the boot process. With enhanced boot integrity and early threat detection, Measured Boot helps create a more secure and trustworthy computing environment, safeguarding the system against unauthorized modifications and firmware-level attacks.