Broken Access Control: Common Types, Risks & How to Prevent It

What is Broken Access Control?

Broken Access Control happens when an application fails to properly enforce user permissions. This allows attackers to perform actions outside their intended privileges—such as accessing another user’s data, changing system settings, or escalating to admin-level access.

These vulnerabilities often go unnoticed during normal use because the app appears to function correctly. However, by manipulating URLs, modifying request parameters, or forcing unauthorized actions, attackers can bypass access restrictions and exploit hidden flaws in the system.

Common Types of Broken Access Control Vulnerabilities

Broken Access Control takes many forms. Here are the most frequent and dangerous patterns:

Vertical Privilege Escalation

When a user with limited rights gains access to high-privilege features like an admin panel it’s called vertical escalation. This often results from missing role checks on backend endpoints. Hiding admin links in the UI isn’t enough; access enforcement must occur server-side.

Example: A standard user directly accesses /admin/deleteUser and successfully deletes user accounts.

Horizontal Privilege Escalation

Here, a user accesses another user’s data at the same privilege level. This usually stems from Insecure Direct Object References (IDOR), where object access is based solely on user input, like an id in the query string.

Example: Changing /user/profile?id=102 to /user/profile?id=103 to view another user’s information.

Unprotected or Obscured Endpoints

Sometimes, developers hide sensitive endpoints using obscure URLs (e.g., /admin-xyz123). But obscurity isn’t protection. Attackers can find these endpoints through source code, JavaScript files, or brute-forcing common paths.

Parameter-Based Role Manipulation

Access should never depend on user-controlled inputs like cookies or query strings. If a role is determined by a parameter (/dashboard?role=admin), attackers can simply modify it to gain access.

Misconfigured Platform-Level Rules

Improper server or framework configurations can open doors. For instance, relying on headers like X-Original-URL for path control without proper validation can allow access bypasses through proxy tricks or request smuggling.

Method and Path Bypass

Some apps enforce controls only for certain HTTP methods or exact path formats. Attackers can change method types (e.g., from POST to GET) or alter URL casing (/Admin/DeleteUser vs /admin/deleteuser/) to sidestep checks.

Chained Escalations

A seemingly minor horizontal escalation can be chained into vertical escalation. For example, compromising a mid-level user’s account via password reset flaws, then using that access to escalate further.

How Broken Access Control Happens

Broken access control often arises from improper enforcement of authorization rules, allowing users to act outside their intended permissions. Here’s a breakdown of how it typically occurs:

1. Over-Reliance on Client-Side Enforcement

Many applications attempt to restrict access by hiding UI elements (like admin links or buttons) or using client-side JavaScript checks. However, this method assumes users won’t manipulate the interface—which is a dangerous assumption.

Attackers can inspect HTML/JavaScript, uncover hidden options, and manually construct requests to access restricted functions. Since enforcement isn’t happening server-side, these client-only controls offer no real protection.

2. Missing or Weak Backend Authorization

Authentication (verifying who a user is) and authorization (verifying what they’re allowed to do) are separate concepts—but are often conflated. Many vulnerabilities arise when applications check if a user is logged in but fail to verify if that user has permission to perform a specific action.

For example, an endpoint like /admin/deleteUser might be accessible to any logged-in user if there’s no role-based check on the backend. Attackers can easily exploit this by modifying requests or guessing endpoint paths.

3. Insecure Direct Object References (IDOR) and Parameter Tampering

This occurs when access to internal objects (like user accounts, documents, or order histories) is granted purely based on user-controlled parameters, such as ?userId=102.

If there’s no proper ownership validation, an attacker can change this ID to view or modify another user’s data. Without object-level permission checks, even non-admin users can perform unauthorized actions.

4. Improper Role and Session Management

Applications sometimes fail to properly update or revoke access when a user’s role changes or after they log out. For example:

• A demoted admin may retain elevated privileges due to cached or outdated session tokens.
• Users may still access restricted resources after logging out if sessions aren’t properly invalidated.
• Temporary privileges might not be revoked after use.

Such oversights lead to lingering access beyond what is intended or safe.

5. Misconfigured or Incomplete Access Control Rules

Many frameworks offer built-in access control mechanisms, but improper configuration can leave gaps. Relying on headers like X-Forwarded-For or X-Original-URL for enforcing access without validation can lead to bypasses—especially when proxies are involved. Similarly, trusting IP-based restrictions without proper checks opens the door to spoofing and privilege escalation.

Risks and Impact of Broken Access Control

Unauthorized Data Exposure: When access controls are weak or misconfigured, attackers can easily view, modify, or extract sensitive information. This could include customer data, internal documents, or application source code. Even a simple IDOR flaw can expose large volumes of confidential data, leading to a serious breach.

Privilege Escalation Attacks: A common consequence of broken access control is privilege escalation—where a user gains more access than they should. For instance, a regular user may manipulate requests or exploit insecure endpoints to gain admin-level privileges, allowing them to alter configurations, access sensitive records, or disrupt operations.

Compliance Failures: Broken access control can breach key compliance mandates like PCI DSS Requirement 7, which enforces role-based access and the principle of least privilege; HIPAA’s Access Control Standard (45 CFR §164.312), which requires technical safeguards to prevent unauthorized access to ePHI; and ISO 27001 Annex A.9, which outlines strict access control policies.Violations can expose sensitive data, lead to non-compliance penalties, and invite regulatory action. Ensuring proper access enforcement is critical for staying audit-ready and maintaining trust.

Business Disruption: Attackers with unauthorized access can manipulate business logic, delete critical data, or disable systems. These disruptions can lead to downtime, service outages, and loss of productivity—impacting both operations and customer experience.

Legal and Financial Consequences: Access control failures often trigger financial loss due to incident response, forensics, and recovery costs. In regulated industries, it could also lead to lawsuits and penalties. Additionally, if customer data is exposed, the resulting reputational damage can lead to lost business and long-term brand erosion.

How to Detect Broken Access Control 

Detecting broken access control involves both proactive testing and continuous monitoring. Here are keyways to uncover these vulnerabilities:

Automated Scanners: Tools like Indusface WAS can identify common patterns of broken access control, such as IDOR vulnerabilities or missing authentication checks on endpoints.

Manual Penetration Testing: In penetration testing, security testers simulate attacks by trying to access restricted areas, elevating privileges, or manipulating parameters (e.g., changing user IDs in URLs). This helps uncover both vertical and horizontal access issues that automation may miss.

Code Reviews: Reviewing backend code helps ensure that access controls are enforced server-side, not just in the frontend. Look for missing role checks, hardcoded roles, or access based solely on user-supplied input.

Security Misconfiguration Testing: Evaluate application and server configuration to detect exposed admin endpoints, improperly set permissions, or insecure URL-based access control mechanisms.

Role-switching tests: These tests help ensure that applications correctly update and enforce permissions when a user’s role changes. They verify that downgraded users immediately lose access to privileged actions and can no longer perform functions tied to their previous role. These tests also check whether the system invalidates or refreshes sessions after a role change to prevent privilege retention.

Logs and analytics

Uncover valuable clues including repeated access attempts to restricted endpoints, unusual access patterns, or unexpected HTTP status codes (such as frequent 403s followed by 200s) which may indicate access misuse.

How to Prevent Broken Access Control Vulnerabilities

Preventing broken access control requires a combination of secure development practices, rigorous testing, and continuous monitoring. Here are key strategies:

1.     Enforce Server-Side Authorization

Client-side restrictions such as hiding buttons or disabling inputs can be easily bypassed. Access control decisions must always be enforced on the server, where users can’t manipulate logic.
Every request should be validated on the backend for the user’s role, ownership of the resource, and specific permissions before granting access. For example, even if a user can see a “Delete” button in the UI, the server should block the request if they lack admin rights.

2. Use Role-Based or Attribute-Based Access Control

Instead of hardcoding rules throughout your app, implement access models like:

• RBAC (Role-Based Access Control): Assign roles (e.g., admin, editor, viewer) with specific permissions.
• ABAC (Attribute-Based Access Control): Enforce access based on user attributes, resource types, and environmental conditions (e.g., location, time of access).

These models centralize access logic and help scale securely across users and systems.

3. Deny by Default

Follow the principle of least privilege: users should only have access to what’s necessary.

By default, assume users should not have access unless explicitly allowed. This prevents accidental exposure of sensitive features or data.

For example, avoid using wildcard permissions like * in APIs or roles that inherit unnecessary privileges.

4. Secure APIs and Endpoints

APIs are prime targets for Broken Access Control. Secure them by:

• Requiring proper authentication and authorization on every endpoint.
• Avoiding predictable object IDs (use UUIDs or indirect references instead).
• Validating access for every operation (GET, POST, PUT, DELETE). Don’t assume prior requests prove future access.
• Also, use OpenAPI specifications to define and enforce expected request structures and roles.

5. Implement Access Control at the Code and Infrastructure Level

Use framework features (like middleware or decorators) to enforce access checks at a central layer in your codebase.
Set access rules at the system layer using tools such as API gateways, reverse proxies, or web application firewalls (WAFs) to restrict traffic.

6. Implement Web Application Firewall

Web Application Firewall (WAF) adds an important layer of defense. It detects and blocks common exploit patterns such as path traversal, predictable endpoint access, and unauthorized role manipulation. By using attack signatures, anomaly detection, and custom access rules, a WAF can prevent attempts to bypass authentication or access restricted resources.

AppTrana WAF also supports virtual patching, which enables quick response to known access flaws without code changes. Combined with detailed logging and traffic insights, a WAF helps enforce strict access policies and reduce exposure to access control vulnerabilities.