CWE-1229: Creation of Emergent Resource

What is Creation of Emergent Resource?

• Overview: Creation of Emergent Resource refers to a vulnerability where software unintentionally creates new resources or behaviors that can be exploited by attackers, deviating from the developer's original intentions.

• Exploitation Methods:

• Attackers can exploit this vulnerability by identifying and leveraging unintended resources or behaviors.
• Common attack patterns include utilizing covert channels or parasitic computing to perform unauthorized actions or computations.

• Security Impact:

• Direct consequences of successful exploitation include unauthorized access to resources or execution of unintended computations.
• Potential cascading effects may involve further compromise of system integrity or confidentiality.
• Business impact could range from unauthorized data access, performance degradation, to increased operational costs due to resource misuse.

• Prevention Guidelines:

• Specific code-level fixes include thorough resource management and explicit declaration of system behaviors.
• Security best practices involve rigorous testing and validation to identify and mitigate unintended system behaviors.
• Recommended tools and frameworks include static analysis tools to detect potential emergent resources and employing security-focused design patterns.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

import os

class FileManager:
    def __init__(self, user_directory):
        self.user_directory = user_directory

    def create_temp_file(self, temp_content):
        # Vulnerable code: creates a temporary file in a user-controlled directory
        temp_file_path = os.path.join(self.user_directory, "temp_file.txt")
        with open(temp_file_path, "w") as temp_file:
            temp_file.write(temp_content)
        return temp_file_path

# In this example, an attacker could potentially fill the user's directory with numerous temporary files,
# causing a denial of service by exhausting disk space. Additionally, storing files in a user-controlled
# directory could lead to unauthorized access or modification of the files.

How to fix Creation of Emergent Resource?

To fix this vulnerability, it is important to limit the creation of temporary resources and control their lifecycle. This can be achieved by:

1. Using a dedicated temporary directory: Instead of creating temporary files in user-controlled directories, use a system-designated temporary directory.
2. Implementing cleanup routines: Ensure that temporary resources are cleaned up after their use.
3. Limiting file creation: Use file-locking mechanisms or counters to limit the number of temporary files created.
4. Using secure temporary file creation functions: Functions that automatically handle file creation and cleanup, like Python's tempfile module, should be utilized.

Fixed Code Example

import tempfile

class FileManager:
    def __init__(self, user_directory):
        self.user_directory = user_directory

    def create_temp_file(self, temp_content):
        # Fixed code: using the secure NamedTemporaryFile function from tempfile module
        with tempfile.NamedTemporaryFile(delete=True, mode='w', suffix='.txt') as temp_file:
            temp_file.write(temp_content)
            temp_file_path = temp_file.name
        return temp_file_path

# The use of tempfile.NamedTemporaryFile ensures that the file is securely created in a temporary directory
# managed by the system. The 'delete=True' parameter ensures that the file is automatically deleted once it
# is closed, preventing resource exhaustion and reducing the risk of unauthorized access.

By implementing these changes, the code is now resilient to attacks that exploit the creation of emergent resources, mitigating the risk of denial of service due to disk space exhaustion and enhancing file security.