What Is Broken Access Control Vulnerability And How to Prevent It

Safeguarding the information we provide online is among the highest priority. One big problem that can make our data vulnerable is something called "broken access control." In this article, we'll explore what broken access control is, why it's dangerous, and how we can protect ourselves from it.

What is Access Control?

Before going into broken access control, let's understand what access control means. Think of access control like a security guard at a building. This guard decides who can enter the building and which rooms they can go into. Access control does the same thing for our apps and websites. It decides who can use certain features or see specific information.

What is Broken Access Control?

Now, imagine if that security guard started making mistakes. Maybe they let people into rooms they shouldn't, or they forget to check ID cards. This is similar to what happens with broken access control in the digital world.

OWASP broken access control is when an app or website doesn't properly control who can do what. It's like leaving the door unlocked to a room full of important secrets. This can lead to big problems, like people seeing information they shouldn't or changing things they're not supposed to.

What is Broken Access Control Vulnerability?

A broken access control vulnerability is a weakness in how an app or website manages who can do what. It's one of the top security risks according to OWASP (Open Web Application Security Project), a non-profit group that offers free and open resources to help make the internet safer.

Here are some examples of broken access control:

1. Letting someone see private information without checking if they're allowed.
2. Allowing a regular user to do things only an admin should do.
3. Letting users change other people's data when they should only be able to change their own.

Types of Access Control Vulnerabilities

There are three main types of access control vulnerabilities:

1. Horizontal Privilege Escalation: This is when two users who should have the same level of access can see each other's private information. It's like if you could suddenly read your neighbour's emails just because you both use the same email service.
2. Vertical Privilege Escalation: This happens when a regular user can do things that only special users (like admins) should be able to do. It's like a student being able to change grades in the school's computer system.
3. Context-Dependent Privilege Escalation: This occurs when users can do things out of order or in ways they shouldn't. For example, if a shopping website lets you change your order after it's already been shipped.

How Broken Access Control Affects API Security

In the modern ecosystem, APIs (Application Programming Interfaces) play a crucial role. They're the connective tissue that allows different software systems to communicate and share data. However, this vital role also makes them a prime target for attackers, and OWASP broken access control in APIs can have far-reaching consequences.

When it comes to API security, broken access control can manifest in several ways:

1. Unauthorised Data Exposure: If an API has broken access controls, it might return data that the requesting user shouldn't have access to. This could lead to massive data breaches if exploited.
2. Unauthorised Functionality Access: A broken access control vulnerability might allow users to access API endpoints or functions they shouldn't be able to use. This could lead to unauthorised activities being taken on the system.
3. Insecure Direct Object References (IDOR): This is a common API vulnerability where an attacker can manipulate the API request to access or modify other users' data. It's a classic example of broken access control in API security.
4. Misconfigured CORS (Cross-Origin Resource Sharing): If CORS is not correctly set up, it might result in compromised access control by enabling unauthorised domains to access important API resources.
5. Lack of Rate Limiting: While not strictly an access control issue, lack of rate limiting can exacerbate broken access control vulnerabilities by allowing attackers to make large numbers of API requests to exploit these flaws.

Common Ways to Find Broken Access Control Vulnerabilities

Security experts use several methods to find broken access control vulnerabilities:

1. Injection Flaws: This is when attackers try to sneak harmful code into an app to make it do things it shouldn't.
2. Cross-Site Scripting (XSS): This happens when attackers can put their own code into a website, which can then run in other users' browsers.
3. Broken Authentication and Session Management: This happens if an app fails to properly manage how users log in and remain logged in.

Real-World Examples of Broken Access Control

Let's look at some real situations where broken access control could cause problems:

1. Online Banking: Imagine if you logged into your bank account and could suddenly see other people's account balances. This would be a serious case of horizontal privilege escalation.
2. School Management System: If a student could access the system and change their grades or view other students' grades, this would be an example of vertical privilege escalation.
3. E-Commerce Website: If a user could view or modify orders that aren't theirs, this would be a broken access control vulnerability.
4. Healthcare Portal: If a patient could access other patients' medical records, this would be a severe breach of privacy due to broken access control.

How to Prevent Broken Access Control Vulnerability

Now that we understand what broken access control is and why it's dangerous, let's look at how we can prevent it:

Continuous Inspection of Access Control

Just like a security guard needs to stay alert, we need to keep checking our access control systems. This means regularly testing and reviewing how we control who can do what in our apps and websites. By doing this, we can quickly spot and fix any new security problems that pop up.

Handle Access Control on the Server Side

It's important to manage access control on the server (the computer that runs the website or app) rather than on the user's device. 

This is because users can sometimes change things on their own devices, but they can't change what happens on the server. By controlling access on the server, we make it much harder for attackers to bypass our security.

Deny Access by Default

A good rule of thumb is to start by not letting anyone access anything unless we specifically allow it. This is like having all doors locked by default and only opening the ones people should be able to use. This approach, sometimes called "Just-In-Time" (JIT) access, helps reduce the risks of giving people too many permissions.

Limiting Cross-Origin Resource Sharing (CORS) Usage

CORS is a way for websites to share resources with each other. While it can be useful, it can also be risky if not set up correctly. By carefully limiting how CORS is used, we can prevent unauthorised access to our resources.

Enable Role-Based Access Control

Role-based access control is like giving people different coloured badges based on their job. Each colour (or role) comes with certain permissions. This makes it easier to manage who can do what, especially in large systems with many users.

Enable Permission-Based Access Control

Permission-based access control is about checking if a user has the right to do something before letting them do it. It's like checking someone's ID before letting them into a restricted area. This helps ensure that users can only access the data and perform the actions they're supposed to.

Enable Mandatory Access Control

Mandatory access control is a strict system where only the admin can change the security rules. Users can't modify these rules themselves. This centralised approach provides a high level of security, especially for very sensitive information.

Best Practices for Implementing Access Control

Here are some additional tips to help prevent broken access control:

1. Use Least Privilege: Only give users the minimum permissions they need to do their job. This limits the damage if an account is compromised.
2. Regularly Update and Patch Systems: Update your software frequently to guard against security vulnerabilities.
3. Log and Monitor Access: Keep track of who's doing what in your system. This can help you spot unusual activity.
4. Educate Users: Find out that your users know the value of security and how to use the system responsibly.
5. Use Secure Session Management: Properly handle how users stay logged in to prevent session hijacking attacks.
6. Implement API Security Best Practices: If your system uses APIs, make sure they're properly secured with authentication and authorisation checks.

The Importance of Regular Security Audits

Regular security audits are crucial in maintaining strong access control. These audits involve thoroughly checking your system for any weaknesses or misconfigurations. They can help you:

• Identify any broken access control vulnerabilities
• Ensure that your access control policies are being properly enforced
• Discover any unauthorised changes to user permissions
• Check that your security measures are up-to-date and effective

Regular auditing helps you to find issues early on and address them before attackers may take advantage of them.

Conclusion

Broken access control is a serious security vulnerability that can lead to unauthorised access to sensitive data and systems. By understanding what it is and how it works, we can take steps to prevent it. Remember, good access control is about making sure the right people have the right access to the right things at the right time.

At InstaSafe, our Zero Trust Network Access (ZTNA) solution directly addresses the challenges of broken access control by implementing robust, context-aware authentication and authorisation for every access request. Through our ZTNA solution, we ensure that only verified users access specific resources, mitigating privilege escalation risks.