Secure Code Review (SCR) : A5 — Security Misconfiguration

Security misconfiguration is a prevalent issue that can occur at any level of an application stack, including the network, platform, web server, application server, database, and code. It happens when security settings are defined, implemented, and maintained improperly. This vulnerability can provide an attacker with unauthorized access to some system data or functionality. In some cases, it may even lead to full system control.

In this blog, we will explore the concept of security misconfiguration, provide examples, and offer a comprehensive checklist for identifying this vulnerability during a secure code review.

Understanding Security Misconfiguration

Security misconfiguration can take many forms, from unnecessary services running on the system to default accounts with weak or well-known passwords, overly permissive file permissions, exposed error handling information, and more.

For example, a web server that exposes a detailed error page with stack traces, database queries, and other sensitive information can provide an attacker with valuable insights into the system’s structure and potential vulnerabilities.

Identifying Security Misconfiguration in Code Review

During a secure code review, it’s essential to identify places where misconfigurations might occur. Here’s what to look for:

1. Unnecessary Features and Services: Look for components, services, features, or functionalities that are enabled but not needed. These can increase the attack surface.
2. Default Accounts and Weak Passwords: Check for default accounts with known usernames and passwords or weak password policies.
3. Overly Verbose Error Handling: Look for error handling that exposes sensitive information like stack traces or SQL queries.
4. Insecure File Permissions: Check for files and directories with permissions that are too permissive, allowing unauthorized access or modification.
5. Misconfigured Cross-Origin Resource Sharing (CORS): Look for improper configurations that allow unauthorized domains to access resources.
6. Insecure Direct Object References (IDOR): Check for instances where user-supplied input is used to access objects directly without proper authorization checks.
7. Lack of Security Headers: Review the application’s HTTP response headers to ensure that security-related headers are properly configured.

Secure Code Review Checklist for Security Misconfiguration

Here’s a checklist to follow when reviewing code for security misconfiguration:

1. Review Configuration Files: Check all configuration files for unnecessary services, default credentials, overly permissive settings, etc.
2. Analyze Error Handling: Ensure that error handling does not reveal sensitive information.
3. Check File and Directory Permissions: Verify that file and directory permissions are set to the least privilege necessary.
4. Review Security Headers: Ensure that security-related HTTP response headers are properly configured.
5. Validate Input and Output: Check that input validation is implemented and that output encoding is used to prevent injection attacks.
6. Review Authentication and Session Management: Ensure that authentication and session management are properly configured.
7. Check CORS Policies: Review CORS policies to ensure that only authorized domains can access resources.
8. Analyze Encryption Settings: Check that encryption is properly configured for data in transit and at rest.

Mitigating Security Misconfiguration

To prevent security misconfiguration, follow these best practices:

1. Minimize Attack Surface: Disable unnecessary features, services, and components.
2. Use Strong Password Policies: Avoid default credentials and enforce strong password policies.
3. Configure Proper Permissions: Set file and directory permissions to the least privilege necessary.
4. Implement Proper Error Handling: Customize error pages to ensure that no sensitive information is exposed.
5. Regularly Update and Patch: Keep all systems and software up to date with the latest security patches.
6. Automate Security Configurations: Use automated tools to manage security configurations and monitor for changes that could introduce vulnerabilities.
7. Conduct Regular Security Audits: Regularly review and audit configurations and settings to ensure ongoing security.

In conclusion, security misconfiguration is a common but preventable vulnerability. By conducting a thorough secure code review and following the best practices outlined above, you can significantly reduce the risk of security misconfiguration in your application. Regular monitoring and auditing are also essential to maintaining a secure configuration over time.