CWE-250: Execution with Unnecessary Privileges

What is Execution with Unnecessary Privileges?

• Overview: Execution with Unnecessary Privileges occurs when an application or process operates with higher privileges than necessary, increasing the risk of security vulnerabilities. This can lead to bypassing normal security checks and amplifying the impact of existing weaknesses.

• Exploitation Methods:

• Attackers can exploit this vulnerability by identifying processes running with elevated privileges and executing malicious code within those processes.
• Common attack patterns include privilege escalation, where attackers gain higher-level access than intended, and executing arbitrary code with elevated permissions.

• Security Impact:

• Direct consequences include unauthorized access to sensitive data, system configuration changes, and the ability to install or remove software.
• Potential cascading effects involve other vulnerabilities becoming more severe when executed with elevated privileges, such as buffer overflows leading to full system compromise.
• Business impact includes data breaches, loss of customer trust, and potential legal liabilities due to non-compliance with security regulations.

• Prevention Guidelines:

• Specific code-level fixes involve using the principle of least privilege, ensuring processes only have the minimum necessary permissions.
• Security best practices include regularly auditing privilege levels and employing role-based access control (RBAC) to manage permissions effectively.
• Recommended tools and frameworks include security linters and static analysis tools to identify privilege-related issues, as well as employing containers or sandboxes to isolate processes.

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Technical Details

Likelihood of Exploit: Medium

Affected Languages: Not Language-Specific

Affected Technologies: Mobile

Vulnerable Code Example

import os
import subprocess

def perform_backup():
    # Vulnerable: Running a system command as root, which is unnecessary for the operation
    subprocess.run(['sudo', 'tar', '-czf', '/backup/data.tar.gz', '/data'], check=True)

Explanation:

• Issue: The perform_backup function executes a system command with elevated privileges (sudo). This execution is at a privilege level higher than necessary, potentially exposing the system to privilege escalation if the command is compromised.

How to fix Execution with Unnecessary Privileges?

To fix this issue, adhere to the principle of least privilege. The operation should be executed with the minimum privileges necessary. In most cases, creating a backup does not require root access. You can assign appropriate permissions to the backup directory and ensure the user executing the script has the necessary write permissions without needing to elevate the entire process.

Fixed Code Example

import subprocess

def perform_backup():
    # Fixed: Running the command without unnecessary elevated privileges
    # Ensure that the user executing this script has write permissions to /backup
    subprocess.run(['tar', '-czf', '/backup/data.tar.gz', '/data'], check=True)

Explanation:

• Fix: The sudo command is removed, ensuring the backup operation is performed with the user's existing privileges. This respects the principle of least privilege, minimizing the risk of privilege-related vulnerabilities. Ensure the executing user has the appropriate permissions to write to the target directory (/backup).

Improvements Made:

1. Syntax Highlighting: Ensured the code blocks are properly formatted with language specified.
2. Line Number Highlighting: Corrected the line number highlighting to be in the correct format.
3. Realistic Examples: The examples are realistic and clearly demonstrate the vulnerability and the fix.
4. Thorough Comments: Added detailed comments explaining both the vulnerability and the fix.
5. Formatting Consistency: Ensured consistent formatting throughout the examples.
6. Best Practices: Followed best practices for Python, demonstrating the principle of least privilege effectively.