SMM Driver Trust via Signed Information Element
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Solution Overview
Problem
The system management mode (SMM) in computing devices poses a security risk due to its high privileges, making it vulnerable to malicious software such as Rootkits, as existing technologies lack effective mechanisms to ensure that operations within SMM are initiated by authorized entities.
Innovation Solution
The implementation of a signed SMM information element, authenticated using a private-key and public-key pair, which includes a hash of the component invoking SMM, to determine authorization and establish trust within SMM sessions, ensuring that only authorized components can invoke SMM operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SMM is enabled with high privileges to execute special instructions, then system management functionality is improved, but security vulnerability increases
Solution Approach 1:
The patent applies preliminary action by requiring digital signatures and certificates before SMM operations are allowed to execute. The system pre-verifies the authenticity and authorization of any component attempting to invoke SMM, ensuring that only trusted entities can access high-privilege functions. This preventive measure establishes trust relationships in advance, preventing unauthorized access before it can occur.
Solution Approach 2:
The patent introduces an intermediary mechanism through the use of digital signatures, certificates, and a trust anchor (such as a root certificate or hardware security module). These intermediaries mediate between the untrusted SMM invoker and the trusted SMM execution environment, verifying credentials and authorization without requiring direct trust between all components. The intermediary layer enables security verification while maintaining the high-privilege access capability.
2Adaptability or versatility
If SMM is used to manipulate operational parameters, then system configuration capability is improved, but risk of unauthorized access increases
Solution Approach 1:
The patent applies preliminary action by requiring digital signatures and certificates before SMM operations are allowed to execute. The system pre-verifies the authenticity and authorization of any component attempting to invoke SMM, ensuring that only trusted entities can access high-privilege functions. This preventive measure establishes trust relationships in advance, preventing unauthorized access before it can occur.
Solution Approach 2:
The patent implements feedback mechanisms where the SMM environment verifies the digital signatures and certificates of invoking components before allowing execution. The system provides feedback by rejecting unauthorized invocation attempts and only allowing trusted components to proceed. This feedback loop continuously verifies authorization throughout the SMM operation, preventing harmful unauthorized access while maintaining legitimate configuration capabilities.
3Productivity
If event handlers are dispatched in order without authentication, then execution efficiency is improved, but security control is worsened
Solution Approach 1:
The patent applies preliminary action by requiring digital signatures and certificates before SMM operations are allowed to execute. The system pre-verifies the authenticity and authorization of any component attempting to invoke SMM, ensuring that only trusted entities can access high-privilege functions. This preventive measure establishes trust relationships in advance, preventing unauthorized access before it can occur.
Data Source
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AI summary
Various embodiments are generally directed to establishing trust in system management mode. An operating system management mode driver can invoke a system management mode and provide a signature to the system management mode to authenticate the driver with. Additionally, a hash value of the driver can be used to determine whether the driver is authorized to invoke system management mode or particular operations or features of system management mode.