API7:2019 Security Misconfiguration

In the previous post we covered API6:2019 Mass Assignment, which was the 6th post in this series. If you want to start from the beginning, go to the first post, API1:2019 Broken Object Level Authorization.

Security misconfiguration has been on the original OWASP Top Ten list (critical web app risks) for many, many years. It basically means lack of hardening, poor implementation, poor maintenance, mistakes, missing patches, and human error. There’s no difference between web apps and APIs for this; if the server and/or network has not been properly secured, your API may be in danger.

What can happen?

Because this category of vulnerability is so vague, the risk is anywhere from low to critical, depending upon what you misconfigured and how you misconfigured it. It could result in a complete system compromise, damage to the confidentiality, availably, and/or integrity of your system, and a plethora of other issues. It could result in as little as embarrassing error messages for the attacker, but no actual impact. That said, this vulnerability should not be taken lightly, it’s on this list for a reason.

How do we avoid such a fate?

Prepare for me to sound like a broken record:

• Follow a secure system development life cycle that includes extensive testing of both the application later, but also the network and infrastructure layer.
• Following the hardening guide for all infrastructure, middleware, COTS, and SaaS products
• Scan (apps, network, infrastructure) continuously
• Create and follow a fast and effective patching process
• Monitor and log all apps, APIs and any other endpoints you have, for potential danger and/or attacks
• Ensure you have access for configuring all of these systems locked down, using the principal of least privilege
• Have an up-to-date and effective incident response (IR) process, and a well-trained IR team

I realize that this blog post is probably not only a bit underwhelming, but you may feel that I have greatly simplified how to avoid this problem. If you feel this way… You’re right. Creating and implementing an effective patch management process in an enterprise is HARD. Continuous scanning is HARD. Getting people to fix misconfigurations (or any vulnerability) that you’ve found is REALLY HARD. None of the things on the list above are easy. Let’s see what the Project Team suggests.

How To Prevent

The API life cycle should include:

• A repeatable hardening process leading to fast and easy deployment of a properly locked down environment.
• A task to review and update configurations across the entire API stack. The review should include: orchestration files, API components, and cloud services (e.g., S3 bucket permissions).
• A secure communication channel for all API interactions access to static assets (e.g., images).
• An automated process to continuously assess the effectiveness of the configuration and settings in all environments.

Furthermore: (From the project team)

• To prevent exception traces and other valuable information from being sent back to attackers, if applicable, define and enforce all API response payload schemas including error responses.
• Ensure API can only be accessed by the specified HTTP verbs. All other HTTP verbs should be disabled (e.g. HEAD).
• APIs expecting to be accessed from browser-based clients (e.g., WebApp front-end) should implement a proper Cross-Origin Resource Sharing (CORS) policy.
  
  

OWASP References (The best kind of references!)

• OWASP Secure Headers Project
• OWASP Testing Guide: Configuration Management
• OWASP Testing Guide: Testing for Error Codes
• OWASP Testing Guide: Test Cross Origin Resource Sharing

In the next blog post we will be talking about API8:2019 Injection.