CWE-1276: Hardware Child Block Incorrectly Connected to Parent System

What is Hardware Child Block Incorrectly Connected to Parent System?

• Overview: Hardware Child Block Incorrectly Connected to Parent System (CWE-1276) occurs when signals between a hardware Intellectual Property (IP) block and the parent system are misconnected, potentially leading to security vulnerabilities despite the system appearing to function correctly.

• Exploitation Methods:

• Attackers could exploit this vulnerability by manipulating the misconnected signals to trigger unauthorized actions or gain access to restricted data within the hardware IP.
• Common attack patterns include forcing the system into a debug mode or exploiting reset functions to manipulate data integrity.

• Security Impact:

• Direct consequences include unauthorized access or modification of data within the hardware IP.
• Potential cascading effects could involve compromised system integrity, leading to broader security breaches.
• Business impact might include data loss, system downtime, and damage to reputation due to security breaches.

• Prevention Guidelines:

• Ensure correct implementation of signal connections between hardware IP and the parent system by thoroughly reviewing and testing design specifications.
• Follow security best practices such as conducting regular security audits and threat modeling to identify potential misconfigurations.
• Utilize recommended tools and frameworks for hardware verification and validation to detect misconnection issues early in the development process.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not Technology-Specific

Vulnerable Code Example

Python Example

class ParentSystem:
    def __init__(self):
        self.data_bus = [0] * 16  # Assuming a 16-bit data bus

    def connect_child(self, child):
        # Vulnerability: Incorrectly connecting the child's data bus by overwriting the parent's data bus
        self.data_bus = child.data_bus  # This overwrites the entire data bus

class ChildBlock:
    def __init__(self):
        self.data_bus = [1] * 16  # Child has its own 16-bit data bus

parent = ParentSystem()
child = ChildBlock()

parent.connect_child(child)

Explanation:

In this vulnerable example, the connect_child method in the ParentSystem class incorrectly connects the child's data bus by directly assigning it to the parent's data bus. This action overwrites the parent's entire data bus, leading to potential data loss and security vulnerabilities if sensitive data was stored in the parent's data bus.

How to fix Hardware Child Block Incorrectly Connected to Parent System?

To address this issue, the connection between the parent's and child's data buses should be handled in a way that merges or interfaces them without overwriting. This can be accomplished by using a specific protocol or logic that appropriately integrates the two data buses, ensuring data integrity and security.

Fixed Code Example

class ParentSystem:
    def __init__(self):
        self.data_bus = [0] * 16  # Initialize with a 16-bit data bus

    def connect_child(self, child):
        # Fix: Safely integrate the child's data bus using a merging strategy
        for i in range(len(child.data_bus)):
            self.data_bus[i] ^= child.data_bus[i]  # Example: Using XOR to combine data safely

class ChildBlock:
    def __init__(self):
        self.data_bus = [1] * 16  # Child has its own 16-bit data bus

parent = ParentSystem()
child = ChildBlock()

parent.connect_child(child)

Explanation:

In the fixed example, the connect_child method now iterates over the child's data bus and safely merges it with the parent's data bus using an XOR operation. This approach ensures that the parent's data bus is not overwritten but instead integrated with the child's data. This method maintains data integrity and enhances security by properly managing the connection between hardware blocks. Depending on the system's requirements, other integration methods such as addition, bitwise operations, or specific mapping strategies could also be utilized.