CWE-1316: Fabric-Address Map Allows Programming of Unwarranted Overlaps of Protected and Unprotected Ranges

What is Fabric-Address Map Allows Programming of Unwarranted Overlaps of Protected and Unprotected Ranges?

• Overview: This vulnerability occurs when the address map in a system's on-chip fabric allows protected and unprotected memory regions to overlap, enabling potential bypass of access controls over sensitive data.

• Exploitation Methods:

• Attackers can exploit this by sending transactions to the overlapping address space, potentially accessing protected data.
• Malicious software can intentionally misconfigure address mappings to create overlaps, granting unauthorized access to restricted areas.

• Security Impact:

• Direct consequences include unauthorized access to sensitive data stored in protected regions.
• Potential cascading effects include data leaks, corruption of sensitive information, and unauthorized system control.
• Business impact could involve loss of intellectual property, violation of privacy regulations, and damage to brand reputation.

• Prevention Guidelines:

• Implement strict validation of address map configurations to ensure no overlaps between protected and unprotected regions.
• Employ robust access control mechanisms that are enforced even in the presence of address map misconfigurations.
• Regularly audit and review address map configurations and access control settings to detect and correct any overlaps.
• Use hardware designs that minimize the need for overlapping address ranges, and employ secure firmware that prevents unauthorized remapping.
• Consider using hardware and software tools that monitor and log access to critical address spaces for suspicious activities.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Bus/Interface Hardware, Not Technology-Specific

Vulnerable Code Example

class MemoryMap:
    def __init__(self):
        # Initialize maps with address ranges
        self.protected_ranges = [(0x1000, 0x2000)]
        self.unprotected_ranges = [(0x1500, 0x2500)]  # Overlaps with protected range

    def is_address_protected(self, address):
        # Check if the address is within any protected range
        for start, end in self.protected_ranges:
            if start <= address < end:
                return True
        return False

    def add_unprotected_range(self, start, end):
        # Add a new unprotected range without checking for overlaps
        self.unprotected_ranges.append((start, end))  # Vulnerable to overlap

Explanation:

• The unprotected_ranges list contains a range (0x1500, 0x2500) that overlaps with the protected_ranges from 0x1500 to 0x2000.
• This overlap allows unauthorized access to the protected memory region, which could lead to security vulnerabilities such as unauthorized data manipulation or leakage.

How to fix Fabric-Address Map Allows Programming of Unwarranted Overlaps of Protected and Unprotected Ranges?

To fix this vulnerability, it's crucial to enforce strict separation between protected and unprotected address ranges. This means implementing checks to prevent overlaps when adding new address ranges. The solution involves:

1. Validation of Address Ranges: Before adding a new unprotected range, validate that it does not overlap with any existing protected range.
2. Robust Error Handling: Provide feedback or raise exceptions when an overlap is detected.
3. Modularize Range Checking: Encapsulate range checking logic for reusability and clarity.

Fixed Code Example

class MemoryMap:
    def __init__(self):
        # Initialize maps with address ranges
        self.protected_ranges = [(0x1000, 0x2000)]
        self.unprotected_ranges = []
    
    def is_address_protected(self, address):
        # Check if the address is within any protected range
        for start, end in self.protected_ranges:
            if start <= address < end:
                return True
        return False

    def add_unprotected_range(self, start, end):
        # Ensure the new range does not overlap with protected ranges
        for p_start, p_end in self.protected_ranges:
            if not (end <= p_start or start >= p_end):  # Check for overlap
                raise ValueError("Unprotected range overlaps with a protected range")  # Raise error if overlap

        # If no overlap, safely add the unprotected range
        self.unprotected_ranges.append((start, end))

Explanation:

• Range Validation: Before adding an unprotected range, the code checks if it overlaps with any protected range. If an overlap is detected, a ValueError is raised to prevent the addition of the range.
• No Overlaps: This ensures that unprotected ranges do not accidentally or maliciously overlap with protected areas, maintaining the integrity of access control.
• Improved Error Handling: Provides clear feedback when an invalid range is attempted to be added, ensuring that the system remains secure against unauthorized access attempts.

This approach ensures that address ranges are strictly managed and access control is enforced, preventing potential security breaches due to overlapping ranges.