CWE-664: Improper Control of a Resource Through its Lifetime

What is Improper Control of a Resource Through its Lifetime?

• Overview: Improper Control of a Resource Through its Lifetime occurs when a program does not correctly manage a resource from its creation to its release, leading to unexpected behaviors and vulnerabilities. This includes mismanagement of objects before they're fully created or after they're marked for destruction.

• Exploitation Methods:

• Attackers can exploit this vulnerability by accessing resources at unintended times, leading to unauthorized actions or data exposure.
• Common attack patterns include use-after-free, double-free, and accessing uninitialized resources.

• Security Impact:

• Direct consequences include program crashes, data corruption, or unauthorized data access.
• Potential cascading effects might involve broader system instability or further vulnerabilities being exposed.
• Business impact could involve data breaches, loss of customer trust, or financial losses due to system downtime or exploitation.

• Prevention Guidelines:

• Specific code-level fixes include ensuring proper initialization and cleanup of resources and using constructs like RAII (Resource Acquisition Is Initialization) in C++.
• Security best practices involve adhering to resource lifecycle policies and regularly auditing code for resource management issues.
• Recommended tools and frameworks include static analysis tools such as Coverity or SonarQube, which can detect resource handling 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

import os

class TemporaryFileManager:
    def create_temp_file(self, file_name):
        # Creates a temporary file but doesn't ensure proper cleanup
        temp_file_path = f'/tmp/{file_name}'
        with open(temp_file_path, 'w') as temp_file:
            temp_file.write('Temporary Data')
        return temp_file_path

# Usage of the TemporaryFileManager
manager = TemporaryFileManager()
file_path = manager.create_temp_file('example.txt')
# Temporary file is not deleted, causing potential resource exhaustion

In this vulnerable code example, a temporary file is created but not properly deleted after use. This can lead to resource exhaustion over time, especially if the method is called frequently. The file remains in the system, potentially consuming disk space unnecessarily.

How to fix Improper Control of a Resource Through its Lifetime?

To fix this vulnerability, it is essential to ensure that resources like temporary files are properly managed throughout their lifecycle. This includes creating the file, using it, and then ensuring it is deleted or closed properly to avoid resource leaks. Using context managers or implementing explicit cleanup functions can help manage the lifecycle of resources effectively.

Best Practices:

1. Use Context Managers: In Python, use with statements to ensure resources are automatically cleaned up.
2. Explicit Cleanup Functions: Implement functions that explicitly delete or close resources when they are no longer needed.
3. Exception Handling: Ensure that cleanup code is executed even if an error occurs during resource usage.

Fixed Code Example

import os

class TemporaryFileManager:
    def create_temp_file(self, file_name):
        # Use context manager to ensure file is closed properly
        temp_file_path = f'/tmp/{file_name}'
        with open(temp_file_path, 'w') as temp_file:
            temp_file.write('Temporary Data')
        return temp_file_path

    def delete_temp_file(self, file_path):
        # Explicitly delete the temporary file to manage resources properly
        if os.path.exists(file_path):
            os.remove(file_path)

# Usage of the TemporaryFileManager
manager = TemporaryFileManager()
file_path = manager.create_temp_file('example.txt')
# Ensure the temporary file is deleted after use
manager.delete_temp_file(file_path)

In the fixed code example, the delete_temp_file method is added to handle the cleanup of temporary files explicitly. The os.remove() function is used to delete the file when it's no longer needed, preventing resource leaks. This ensures proper control over the resource throughout its lifetime. Additionally, using a context manager ensures that the file is properly closed after writing, even if an error occurs.