Description:

   - Summary: Broken Access Control is a serious and frequent security problem that happens when an application does not correctly enforce rules about what different users can or cannot do. Essentially, when access control is broken, the application might not check properly whether a user has the right permissions before allowing them to access certain features or data.

As a result, this can lead to several issues:

   - Unauthorized Access: Users might be able to view or manipulate data that they should not have access to. For example, a regular user might be able to see confidential information meant only for administrators.

• Unauthorized Actions: Users could perform actions they are not allowed to, such as deleting records or modifying settings, which can disrupt the application’s functionality or compromise its security.

  • Potential Full Control: In severe cases, attackers might gain enough access to take complete control over the application, leading to major security breaches or system compromises.

OWASP and CWE Tags:

   - OWASP Tag: A5:2017 Broken Access Control/ A01:2021 - Broken Access Control

• CWE Tag: CWE-284 (Improper Access Control), CWE-639 (Authorization Bypass Through User-Controlled Key), CWE-862 (Missing Authorization)

History of Origin:

• Origin Date: Early 2000s

• First Documented Case: One of the early documented cases was in the mid-2000s when web applications began to expose sensitive resources through URLs or improperly secured endpoints, leading to unauthorized access.

• Evolution: Initially identified in the early 2000s as web applications began to adopt more complex architectures, Broken Access Control vulnerabilities became more prominent as developers overlooked proper access restrictions. The rise of APIs, microservices, and single-page applications further expanded the attack surface, making it critical to enforce strict access controls throughout the development process.

How it is Exploited:

• Method: Attackers exploit Broken Access Control by manipulating requests to gain unauthorized access to resources or perform actions beyond their intended permissions. Here are some common and additional attack vectors:

  • Insecure Direct Object References (IDOR): Attackers manipulate URL parameters, such as object IDs or file names, to access resources they should not be able to. For instance, by changing a user ID in the URL, an attacker might view or modify another user's data, such as personal information or transaction records.
  • Privilege Escalation: Attackers exploit weaknesses in role-based access control systems to gain higher levels of access than intended. For example, if a regular user can somehow gain access to admin functions, they might perform actions like changing system settings or accessing restricted data.
  • Forced Browsing: Attackers manually attempt to access sensitive pages or endpoints by directly typing URLs or manipulating requests. This technique allows attackers to discover and exploit hidden or poorly protected areas of the application, such as administrative pages or user account settings.
  • Function Level Access Control Issues: Attackers access restricted functions or features by bypassing checks that should validate user permissions. For example, if an API endpoint does not properly check whether a user has the right to invoke a specific function, an attacker could exploit this to perform unauthorized actions.
  • Missing Authorization: Attackers exploit applications where authorization checks are missing or not enforced properly. This might occur if an application relies on client-side controls instead of server-side checks, allowing attackers to bypass security mechanisms.
  • Insecure URL Manipulation: Attackers alter URLs to trick the application into providing access to restricted resources. For example, modifying query parameters or path segments in URLs might allow unauthorized access to files or data.
  • Unintended Data Exposure: Attackers exploit flaws that lead to the exposure of sensitive data through URLs, error messages, or debug information. This can happen if access controls are not properly enforced on data retrieval functions, making it possible to access sensitive information by simply requesting it.

How it is Escalated with Other Vulnerabilities for Higher Impact:

Escalation Techniques:

• Privilege Escalation: Attackers can use Broken Access Control together with weaknesses in authentication or session management to gain higher levels of access than they are supposed to. For example, if a regular user can exploit these flaws, they might gain admin-level access, allowing them to change critical settings, view confidential data, or control the entire application. This often happens when the application does not properly check and enforce user roles and permissions.

• Cross-Site Scripting (XSS): When combined with Broken Access Control, XSS can be used to steal users' login credentials or session tokens. These stolen credentials can then be used to bypass access controls, giving attackers unauthorized access to accounts or sensitive areas of the application. For instance, if an attacker injects a malicious script into a web page, it might capture users' session cookies, which can be used to impersonate those users.

• Cross-Site Request Forgery (CSRF): Attackers can use CSRF attacks to exploit Broken Access Control by tricking users into performing actions on an application without their knowledge. For example, an attacker might create a fake form or link that, when clicked by an authenticated user, performs an action such as changing account settings or transferring funds without the user’s consent. If the application doesn’t properly check that requests come from authorized users, it can allow these unauthorized actions.

• Session Fixation: Attackers might exploit Broken Access Control by fixing a user’s session ID. If they can get a victim to use a session ID controlled by the attacker, they might be able to access restricted parts of the application. This can be particularly dangerous if the application doesn’t properly validate session IDs.

• URL Manipulation: Attackers can manipulate URLs to access restricted resources or functionalities. For example, changing parameters in the URL might allow attackers to view or edit data that they should not have access to, such as accessing another user’s account or administrative features.

• API Abuse: Attackers might abuse poorly secured APIs to gain access to restricted data or functionalities. For example, if an API endpoint is not properly protected and an attacker can guess or find the endpoint, they might be able to perform actions or retrieve information they shouldn’t be able to.

• Forced Access: Attackers can attempt to access sensitive resources or perform restricted actions by directly navigating to or invoking protected URLs or functions. This technique often involves guessing or discovering hidden endpoints that are not properly secured.

How to Remediate:

• Enforce Proper Access Controls: Make sure to set up and enforce strict access control rules for every part of your application. This means that users should only be able to access data and perform actions that are allowed based on their specific permissions. For example, a regular user should not be able to access administrative functions or view data meant only for administrators.

• Role-Based Access Control (RBAC): Implement role-based access control to manage what different users can do based on their roles. Define roles clearly, such as “admin,” “user,” or “guest,” and make sure that users only get the permissions needed for their role. This prevents users from having more access than necessary, minimizing the potential for abuse.

• Deny by Default: Follow a "deny-by-default" approach, where access is automatically denied unless it is explicitly granted. This means that unless you specifically allow a user to access certain resources or perform certain actions, they should not be able to do so. This approach helps to reduce the risk of unauthorized access by default.

• Conduct Regular Access Control Audits: Regularly check and test your access control systems to make sure they are working as intended. This includes reviewing user permissions, testing access control rules, and fixing any issues or gaps that you find. Regular audits help to identify and address problems before attackers can exploit them.

  • Use Security Frameworks: Utilize security frameworks and libraries that offer built-in features for managing access control. These tools often come with best practices and pre-built functionalities that help ensure proper access control. For example, frameworks like Spring Security for Java applications provide robust security features to manage user access and protect sensitive data.

How to Test:

• Automated Scanning: Use automated tools to check for access control problems. Tools like OWASP ZAP, Burp Suite, or Acunetix can scan your application for vulnerabilities that might allow unauthorized access to sensitive parts of the system. These tools help identify issues quickly by testing various parts of your application and reporting where access controls might be weak or missing.

• Manual Testing: Perform manual testing by trying to access restricted areas of the application yourself. This involves changing URL parameters, IDs, or session tokens to see if you can reach parts of the application that should be off-limits. For example, try altering user IDs in URLs to check if you can access another user's information or changing session tokens to see if you can gain unauthorized access.

• Role-Based Testing: Test your application with different user accounts that have various roles, such as admin, regular user, or guest. This helps ensure that the application enforces access controls correctly for each role. Make sure that users with lower privileges cannot access features or data meant only for higher-level roles. For instance, verify that a regular user cannot access admin functions or view restricted data.

• Forced Browsing: Attempt to access hidden or unlisted URLs directly by guessing or discovering them. This method checks if sensitive pages or endpoints that are not linked or visible in the user interface are still properly protected. For example, try entering URLs that are not easily accessible through normal navigation to see if you can reach restricted sections without authorization.

Reference Links of Blogs:

• Blog 1: All About Broken Access Control

• Blog 2: Access control vulnerabilities and privilege escalation