BIOS Credential Interface for Unauthorized Boot Prevention
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Solution Overview
Problem
Automated Teller Machines (ATMs) are vulnerable to security breaches when booted from locations other than their hard disk, as conventional system firmware does not consistently require authentication for alternative boot locations, allowing malicious OS or software to load and compromise the system.
Innovation Solution
The implementation of a BIOS credential interface that enforces a policy requiring a valid password every time the ATM is booted from a location other than its hard disk, using a credential manager to periodically change and verify credentials, ensuring that only authorized boots from alternative locations occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the system firmware automatically boots from an external disc or memory stick during initial boot, then the booting process is simplified and faster, but the ATM becomes vulnerable to security breaches allowing unauthorized software to compromise the system
Solution Approach 1:
The system performs preliminary authentication by detecting whether the firmware is in secure mode before allowing boot from external media. This preliminary check prevents unauthorized boots before the security breach can occur, while still allowing legitimate service operations when properly authenticated.
Solution Approach 2:
A secure mode flag acts as an intermediary between the boot request and the actual boot execution. This flag mediates the boot process by enabling or disabling external media boot based on the security state, preventing direct unauthorized access while maintaining controlled legitimate access.
2Ease of operation
If the system firmware presents a password screen for boot configuration but does not require subsequent passwords after initial authentication, then the ease of operation improves for legitimate service, but the security is compromised allowing intruders to boot from alternative locations
Solution Approach 1:
The system implements periodic authentication by resetting the secure mode flag after each successful boot from external media. This requires re-authentication for each subsequent boot attempt, maintaining security while allowing legitimate service operations to proceed efficiently with proper credentials.
Solution Approach 2:
The secure mode flag dynamically changes state between set and cleared conditions based on authentication outcomes. This dynamic behavior allows the system to adapt its security requirements in real-time, requiring authentication only when transitioning to a less secure state while maintaining ease of operation during authorized sessions.
3Productivity
If the system allows boot from alternative locations without consistent password requirements, then the productivity of service operations increases, but the loss of information and security breaches increase
Solution Approach 1:
The system uses feedback from the secure mode flag state to determine whether authentication is required. This feedback mechanism ensures that security requirements are consistently applied based on the current security state, preventing information loss through unauthorized boots while maintaining productivity for authorized operations.
Data Source
AI summary
A Basic Input/Output System (BIOS)/Unified Extensible Firmware Interface (UEFI) on a Self-Service Terminal (SST) loads ATM resources into volatile memory of the SST during a boot of the SST in a predefined order. Each time, during an SST boot, where the order is attempting to be changed; a credential is required to change the predefined order and the credential has to be authenticated before the predefined order is changed during the SST boot.