CWE-1310: Missing Ability to Patch ROM Code

What is Missing Ability to Patch ROM Code?

• Overview: Missing Ability to Patch ROM Code (CWE-1310) is a vulnerability where systems or System-on-Chips (SoCs) rely on ROM code that cannot be updated or patched after deployment. If vulnerabilities are discovered in this ROM code, they cannot be fixed, leaving the system perpetually vulnerable.

• Exploitation Methods:

• Attackers can exploit this by identifying and targeting vulnerabilities within the immutable ROM code.
• Common attack patterns include leveraging known vulnerabilities to bypass security mechanisms like Root-of-Trust (RoT).

• Security Impact:

• Direct consequences include the inability to fix security vulnerabilities, leading to potential unauthorized access or control of the system.
• Potential cascading effects include the compromise of other systems or components relying on the affected SoC.
• Business impact can include data breaches, loss of customer trust, legal liabilities, and financial losses.

• Prevention Guidelines:

• Specific code-level fixes are not applicable since ROM is immutable; however, planning for patchability in future designs is crucial.
• Security best practices include using a layered security approach and ensuring critical security code is not hardcoded into ROM.
• Recommended tools and frameworks involve utilizing hardware that supports secure firmware updates and designing systems with updatable components outside of ROM where possible.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: System on Chip

Vulnerable Code Example

class FirmwareLoader:
    def __init__(self):
        # ROM code is hardcoded in the firmware and cannot be updated
        self.rom_code = "vulnerable_rom_code"

    def load_firmware(self):
        # Loads the ROM code into the system
        print("Loading ROM code:", self.rom_code)

Explanation

In this vulnerable code example, the ROM code is hardcoded within the class, which means it cannot be updated or patched. If a security flaw is discovered in the ROM code, the system remains vulnerable since there is no mechanism to update or patch it. This represents a significant security risk because any discovered vulnerabilities cannot be mitigated without the ability to update the ROM.

How to fix Missing Ability to Patch ROM Code?

To fix this vulnerability, you should implement a mechanism that allows for updating or patching the ROM code. This can be achieved by storing the ROM code externally, such as retrieving it from a secure server or using an updateable configuration file. Additionally, implement proper version control and digital signatures to verify the integrity and authenticity of the ROM code.

Fixed Code Example

import requests

class FirmwareLoader:
    def __init__(self, firmware_url):
        self.firmware_url = firmware_url

    def load_firmware(self):
        # Fetches the updated ROM code from a secure server
        try:
            response = requests.get(self.firmware_url, timeout=10)
            response.raise_for_status()  # Ensure we catch HTTP errors
            rom_code = response.text
            # Verify the digital signature of the ROM code
            if self.verify_signature(rom_code):
                print("Loading ROM code:", rom_code)
            else:
                raise ValueError("Invalid ROM code signature!")
        except requests.RequestException as e:
            print(f"Failed to fetch ROM code: {e}")

    def verify_signature(self, rom_code):
        # Placeholder for signature verification logic
        # Implement actual signature verification logic here
        return True

Explanation of the Fix

• The ROM code is dynamically fetched from a secure URL, allowing for updates and patches if vulnerabilities are discovered.
• A digital signature verification function verify_signature() is implemented to ensure that the ROM code has not been tampered with, providing integrity and authenticity.
• The use of exceptions to handle network errors ensures that the system can gracefully handle issues related to fetching the ROM code.
• This approach ensures that the system can be kept up-to-date with the latest security patches, significantly reducing the risk of exploitation due to outdated ROM code.