CWE-1260: Improper Handling of Overlap Between Protected Memory Ranges

What is Improper Handling of Overlap Between Protected Memory Ranges?

• Overview: Improper Handling of Overlap Between Protected Memory Ranges occurs when a software system allows different memory regions to overlap in a way that can unintentionally bypass memory protection mechanisms, potentially leading to security vulnerabilities.

• Exploitation Methods:

• Attackers can exploit this vulnerability by causing a lower-privileged software component to overlap its memory region with a higher-privileged one, thereby accessing or altering protected memory.
• Common attack patterns include manipulating memory remapping functions or exploiting flaws in the memory protection unit (MPU) logic to gain unauthorized access.

• Security Impact:

• Direct consequences of successful exploitation include unauthorized read or write access to protected memory, leading to information disclosure or unauthorized modification.
• Potential cascading effects include privilege escalation, where attackers gain higher-level access than intended, and denial of service, impacting system stability and reliability.
• Business impact may involve data breaches, loss of sensitive information, compromised system integrity, and potential legal and financial repercussions.

• Prevention Guidelines:

• Specific code-level fixes include ensuring strict validation and verification of memory region definitions and avoiding overlapping address regions unless absolutely necessary.
• Security best practices involve implementing rigorous access control policies and regularly auditing memory management logic to ensure compliance with security standards.
• Recommended tools and frameworks include using static analysis tools to detect overlapping memory regions and employing hardware-based memory protection mechanisms to enforce isolation.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Memory Hardware, Processor Hardware

Vulnerable Code Example

Python Example

class MemoryManager:
    def __init__(self):
        self.memory_blocks = []

    def allocate_memory(self, start, size):
        # Vulnerable code: Allows overlapping regions which can bypass memory protection
        self.memory_blocks.append((start, start + size))
        print(f"Memory allocated from {start} to {start + size}.")

    def check_overlap(self, new_start, new_end):
        # This method checks if the new memory block overlaps with any existing blocks
        for start, end in self.memory_blocks:
            if new_start < end and new_end > start:
                return True
        return False

    def use_memory(self, start, size):
        if not self.check_overlap(start, start + size):
            print("Memory block is free to use.")
        else:
            print("Memory block overlaps with an existing block.")

Explanation

In this code, the allocate_memory method allows users to allocate memory without checking for overlapping regions. This creates a vulnerability where overlapping memory blocks can lead to unauthorized data access or corruption. The lack of an overlap check before appending to self.memory_blocks means that memory protection can be bypassed, as two or more blocks may share the same space.

How to fix Improper Handling of Overlap Between Protected Memory Ranges?

Fixed Code Example

class MemoryManager:
    def __init__(self):
        self.memory_blocks = []

    def allocate_memory(self, start, size):
        # Fixed code: Check for overlap before allowing allocation
        if not self.check_overlap(start, start + size):
            self.memory_blocks.append((start, start + size))
            print(f"Memory allocated from {start} to {start + size}.")
        else:
            raise ValueError("Memory allocation failed due to overlap.")

    def check_overlap(self, new_start, new_end):
        # This method checks if the new memory block overlaps with any existing blocks
        for start, end in self.memory_blocks:
            if new_start < end and new_end > start:
                return True
        return False

    def use_memory(self, start, size):
        if not self.check_overlap(start, start + size):
            print("Memory block is free to use.")
        else:
            print("Memory block overlaps with an existing block.")

Explanation

In the fixed code, the allocate_memory method now includes a check for overlap before appending a new memory block to self.memory_blocks. If an overlap is detected, a ValueError is raised, preventing the allocation and thus maintaining memory integrity and protection. This ensures that all allocated memory regions are distinct and non-overlapping, adhering to best practices for memory management. The code now properly handles potential overlaps, ensuring that memory protection is not bypassed.