CWE-1257: Improper Access Control Applied to Mirrored or Aliased Memory Regions

What is Improper Access Control Applied to Mirrored or Aliased Memory Regions?

• Overview: Improper Access Control Applied to Mirrored or Aliased Memory Regions (CWE-1257) occurs when hardware designs implement memory protection inconsistently across aliased or mirrored memory regions, allowing unauthorized access to protected memory.

• Exploitation Methods:

• Attackers can exploit this vulnerability by accessing memory through an aliased address with weaker permissions.
• Common attack patterns include bypassing primary memory region protections by targeting aliased regions, potentially altering or reading sensitive data.

• Security Impact:

• Direct consequences include unauthorized read/write access to protected memory areas.
• Potential cascading effects involve the compromise of data integrity and confidentiality, leading to broader system vulnerabilities.
• Business impact may include data breaches, loss of intellectual property, and damage to reputation.

• Prevention Guidelines:

• Specific code-level fixes include ensuring consistent access control across all memory aliases.
• Security best practices involve rigorous testing of memory access controls and implementing comprehensive hardware security features.
• Recommended tools and frameworks include using hardware design verification tools to detect and correct inconsistent memory protection settings.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Memory Hardware, Processor Hardware, Microcontroller Hardware, Network on Chip Hardware, System on Chip

Vulnerable Code Example

Python Example

class MemoryRegion:
    def __init__(self):
        # Simulated memory regions with different access controls
        self.protected_region = [0] * 100  # Only admin should access
        self.mirrored_region = self.protected_region  # Alias of protected_region

    def write_to_region(self, user, index, value):
        # Inadequate access control for mirrored region
        if user == 'admin':
            self.protected_region[index] = value  # Proper access control
        else:
            # Improper access control: non-admin can modify protected_region via mirrored_region
            self.mirrored_region[index] = value

# Simulated usage
memory = MemoryRegion()
memory.write_to_region('guest', 5, 42)  # Unintended write access by guest

Explanation:

• The mirrored_region is an alias for protected_region, but only the protected_region has access control checks.
• A non-admin user can write to mirrored_region, which inadvertently modifies protected_region, violating access control policies.

How to fix Improper Access Control Applied to Mirrored or Aliased Memory Regions?

To fix this vulnerability, apply consistent access control checks across all aliased or mirrored memory regions. Ensure that access permissions are enforced uniformly regardless of the memory region being accessed. The code should check user permissions before allowing writes to any region, ensuring that the access control policy is consistently applied.

Fixed Code Example

class MemoryRegion:
    def __init__(self):
        # Simulated memory regions with proper access control implementation
        self.protected_region = [0] * 100  # Only admin should access
        self.mirrored_region = self.protected_region  # Alias of protected_region

    def write_to_region(self, user, index, value):
        # Consistent access control applied to all memory regions
        if user != 'admin':
            raise PermissionError("Access denied: unauthorized user cannot write to protected regions.")
        self.protected_region[index] = value  # Access control applied here ensures both regions are protected

# Simulated usage
memory = MemoryRegion()
try:
    memory.write_to_region('guest', 5, 42)  # Will raise PermissionError
except PermissionError as e:
    print(e)  # Properly handles unauthorized access

Explanation:

• Both protected_region and mirrored_region are now protected by consistent access control checks.
• Only authorized users (e.g., 'admin') are allowed to modify these regions.
• Unauthorized access attempts are caught and handled, ensuring the integrity of the protected_region.