CWE-732: Incorrect Permission Assignment for Critical Resource

What is Incorrect Permission Assignment for Critical Resource?

• Overview: Incorrect Permission Assignment for Critical Resource occurs when a software application assigns permissions to a resource in a way that allows unauthorized users to access or modify it. This typically happens when permissions are too broadly defined, granting access to more users than necessary.

• Exploitation Methods:

• Attackers can exploit this vulnerability by identifying and accessing resources with overly permissive settings.
• Common attack patterns include scanning for misconfigured permissions on cloud storage, databases, or configuration files.

• Security Impact:

• Direct consequences include unauthorized access to sensitive data and potential data modification or deletion.
• Potential cascading effects include data breaches, loss of integrity of critical resources, and compromised system configurations.
• Business impact may involve financial loss, reputational damage, and legal penalties due to data protection regulations.

• Prevention Guidelines:

• Specific code-level fixes involve setting permissions to the least privilege necessary for each user or process.
• Security best practices include regular audits of permission settings and employing role-based access control (RBAC).
• Recommended tools and frameworks include using cloud security configuration management tools and access control analysis tools to detect and fix permission misconfigurations.

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Technical Details

Likelihood of Exploit: High

Affected Languages: Not Language-Specific

Affected Technologies: Not Technology-Specific, Cloud Computing

Vulnerable Code Example

import os

# Vulnerable code: assigning overly permissive file permissions
def create_config_file():
    # Create a configuration file with critical information
    with open('config.txt', 'w') as config_file:
        config_file.write('secret_key=supersecret\n')
    
    # Set file permissions to be readable and writable by everyone
    os.chmod('config.txt', 0o777)  # This is too permissive and exposes the file to unintended actors

Explanation:

• The function create_config_file creates a file config.txt containing sensitive information like a secret key.
• The permission 0o777 allows the file to be read, written, and executed by any user, which is highly insecure for a file containing sensitive information.
• This could lead to unauthorized access and potential data leakage or tampering.

How to fix Incorrect Permission Assignment for Critical Resource?

To fix this issue, ensure that the file permissions are set to only allow the necessary access. For a sensitive configuration file, it should typically be readable and writable only by the owner. This can be done by setting the permission to 0o600 or 0o640, depending on whether you need group read access. Here are the steps:

1. Restrict Permissions: Use restrictive permissions that only allow the file owner to read and write the file.
2. Use Security Best Practices: Always follow the principle of least privilege, granting only the minimum permissions necessary for functionality.

Fixed Code Example

import os

# Fixed code: assigning restrictive file permissions
def create_config_file():
    # Create a configuration file with critical information
    with open('config.txt', 'w') as config_file:
        config_file.write('secret_key=supersecret\n')
    
    # Set file permissions to be readable and writable only by the owner
    os.chmod('config.txt', 0o600)  # This restricts access to the file, enhancing security

Explanation:

• The function create_config_file now sets the file permissions to 0o600, meaning it is readable and writable only by the owner.
• This change ensures that unauthorized users cannot access or modify the critical resource, thereby securing it against unintended actors.
• By following the principle of least privilege, we significantly reduce the risk of unauthorized access to sensitive information.