CWE-1233: Security-Sensitive Hardware Controls with Missing Lock Bit Protection

What is Security-Sensitive Hardware Controls with Missing Lock Bit Protection?

• Overview: This vulnerability occurs when a hardware system uses a register lock bit to protect sensitive controls but fails to ensure it effectively prevents unauthorized modifications. This can leave critical hardware configuration open to tampering.

• Exploitation Methods:

• Attackers can exploit this by using software to access and modify system registers that should be protected by the lock bit.
• Common attack patterns include bypassing insufficient lock mechanisms to alter memory configurations or other hardware settings.

• Security Impact:

• Direct consequences include unauthorized changes to critical hardware configurations, potentially compromising system integrity.
• Potential cascading effects involve further exploitation of weakened system defenses, leading to broader system breaches.
• Business impact can include data breaches, loss of customer trust, and financial repercussions due to compromised systems.

• Prevention Guidelines:

• Specific code-level fixes include verifying that lock bits effectively secure all relevant registers and controls, ensuring no unauthorized modifications.
• Security best practices involve implementing comprehensive testing of lock bit mechanisms to prevent circumvention.
• Recommended tools and frameworks include hardware security analysis tools and robust verification processes to ensure lock bit effectiveness.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not Technology-Specific

Vulnerable Code Example

class HardwareController:
    def __init__(self):
        self.registers = {
            "config_register": 0x00,  # Configuration register
            "lock_bit": 0x00          # Lock bit register
        }

    def update_register(self, register_name, value):
        # Vulnerability: The lock bit is not checked before updating registers
        # This allows unauthorized modifications to critical hardware settings
        self.registers[register_name] = value  # Directly updates without validation

Explanation:

• Vulnerability: The update_register method directly modifies hardware configuration registers without verifying if the lock bit is set. This oversight can lead to unauthorized changes to critical system settings, posing a security risk.

How to fix Security-Sensitive Hardware Controls with Missing Lock Bit Protection?

Fixed Code Example

class HardwareController:
    def __init__(self):
        self.registers = {
            "config_register": 0x00,  # Configuration register
            "lock_bit": 0x00          # Lock bit register
        }

    def update_register(self, register_name, value):
        # Fix: Check if the lock bit is set before allowing modifications
        if self.registers["lock_bit"] == 0x01:  # Ensure lock bit is set
            self.registers[register_name] = value  # Safe to update
        else:
            raise PermissionError("Modification denied: Register is locked.")  # Prevent unauthorized changes

Explanation:

• Fix Implemented: Before allowing a register update, the code now checks if the lock_bit is set (0x01). If the lock bit is not set, it raises a PermissionError, effectively preventing unauthorized modifications. This ensures that only authorized changes are made to critical hardware settings.
• Security Control: By adding this lock bit verification, we ensure that security-sensitive hardware controls are protected from unauthorized modifications, adhering to best security practices.