CWE-1266: Improper Scrubbing of Sensitive Data from Decommissioned Device

What is Improper Scrubbing of Sensitive Data from Decommissioned Device?

• Overview: Improper Scrubbing of Sensitive Data from Decommissioned Device occurs when a product fails to provide an adequate way for an administrator to thoroughly remove sensitive data when the product is taken out of service. This vulnerability can result from a lack of scrubbing features, or if the scrubbing process is incomplete or incorrect.

• Exploitation Methods:

• Attackers can exploit this vulnerability by accessing decommissioned devices and extracting leftover sensitive data.
• Common attack patterns include physical access to the device, data recovery techniques, and leveraging forensic tools to retrieve data that wasn't properly erased.

• Security Impact:

• Direct consequences include unauthorized access to sensitive data such as credentials, proprietary information, and network configurations.
• Potential cascading effects involve unauthorized network access, data breaches, and further exploitation of connected systems.
• Business impact can include loss of reputation, legal ramifications, and financial loss due to data breaches and compliance failures.

• Prevention Guidelines:

• Implement secure deletion algorithms that overwrite data multiple times to ensure it is irrecoverable.
• Follow security best practices like using cryptographic erase functions and ensuring all storage media are sanitized before decommissioning.
• Recommended tools and frameworks include data wiping software and compliance with standards such as NIST SP 800-88 for media sanitization.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not Technology-Specific

Vulnerable Code Example

import os

def decommission_device(device_path):
    # This function attempts to decommission a device by deleting its files
    try:
        os.remove(device_path)  # This only deletes the file reference, not the data
        print(f"Device {device_path} decommissioned.")
    except Exception as e:
        print(f"Error decommissioning device: {e}")

Explanation:

• Vulnerability: The code uses os.remove() to delete the file reference, but the actual data remains on the storage medium. This data can potentially be recovered using data recovery tools, posing a security risk if the file contains sensitive information.

How to fix Improper Scrubbing of Sensitive Data from Decommissioned Device?

To properly scrub sensitive data from a decommissioned device, overwrite the file contents before deleting it. This ensures that the data cannot be easily recovered. A common approach is to overwrite the file with random data or zeros multiple times. Additionally, using a secure deletion tool or library can further ensure data is irrecoverable.

Fixed Code Example

import os

def secure_delete(file_path, passes=3):
    """Overwrite the file with random data to securely erase it."""
    try:
        with open(file_path, "r+b") as f:
            length = os.path.getsize(file_path)
            for _ in range(passes):
                f.seek(0)
                f.write(os.urandom(length))  # Overwrite with random data
                f.flush()
                os.fsync(f.fileno())  # Ensure data is written to disk
        os.remove(file_path)  # Finally, delete the file
    except Exception as e:
        print(f"Error securely deleting file: {e}")

def decommission_device(device_path):
    # Securely delete the device file
    secure_delete(device_path)  # Use secure delete instead of simple remove
    print(f"Device {device_path} securely decommissioned.")

Explanation:

• Fix: The secure_delete function overwrites the file contents with random data multiple times before removing the file. This reduces the risk of the data being recoverable.
• Best Practices:
  • Overwrite sensitive data multiple times to make recovery difficult.
  • Use secure libraries or tools specialized for data erasure when possible.
  • Handle exceptions to ensure the process completes or reports failures for further action.
  • Use fsync() to ensure data is physically written to disk.

This fix ensures that sensitive data is properly scrubbed from the device, adhering to best practices for secure data deletion.