Understanding Access Control

Welcome to BBX: Empowering Your Cyber Security Journey

3 min readOct 4, 2023

Load your bytes and let’s start today we are going to demystify access control vulnerability it is the linchpin of web application security. It dictates who or what has the authorization to perform actions or access specific resources within an application. This article delves into the nuances of access control, with a special focus on two critical vulnerabilities: vertical and horizontal privilege escalation.

Understanding Access Control:

Access control encompasses three key components:

  1. Authentication:
  • Verification of a user’s identity.

2. Session Management:

  • Identification of subsequent HTTP requests from the same user.

3. Access Control:

  • Decision-making process to grant or deny a user’s requested action.

Vertical Privilege Escalation:

Vertical privilege escalation is a scenario where a user gains access to functionalities they are not supposed to have access to. This can have serious implications for security.

Unprotected Functionality:

This arises when sensitive functionalities lack the necessary protection. Even if administrative functions are not directly linked, a user might still access them via the relevant URL.


  • A website hosts sensitive functionality at https://bbx-insecure-website.com/admin, accessible to any user. Attackers may discover this URL through means like brute-forcing.

Security by Obscurity:

Some applications attempt to conceal sensitive functionality by using less predictable URLs. However, this is not a foolproof method, as users may still discover the obfuscated URL through various means.


  • An application uses the URL https://bbx-insecure-website.com/administrator-panel-yb556. While not easily guessable, the application might inadvertently leak this URL through scripts constructing the user interface.
var isAdmin = false;
if (isAdmin) {
var adminPanelTag = document.createElement('a');
adminPanelTag.setAttribute('href', 'https://bbx-insecure-website.com/administrator-panel-yb556');
adminPanelTag.innerText = 'Admin panel';
// Additional code for appending the element to the DOM or performing other actions.

Parameter-Based Access Control:

Certain applications determine a user’s access rights or role at login and store this information in user-controllable locations like hidden fields, cookies, or preset query string parameters.


This approach is insecure, as users can potentially modify these values to gain unauthorized access.

Horizontal Privilege Escalation:

Horizontal privilege escalation occurs when a user accesses resources belonging to another user instead of their own. This is a critical security concern.


  • An employee accessing the records of other employees, in addition to their own.

Horizontal to Vertical Privilege Escalation:

A horizontal privilege escalation attack can lead to vertical escalation by compromising a more privileged user. This is a significant escalation in security risk.


  • Gaining access to an administrative account through parameter tampering.

Note on Insecure Direct Object Reference (IDOR) Vulnerabilities:

Insecure direct object references (IDORs) are a type of access control vulnerability that occurs when user-controlled parameter values are used to directly access resources or functions. This can allow attackers to access sensitive data or modify system settings without having to authenticate or obtain authorization.

IDOR vulnerabilities can be exploited in a number of ways. For example, an attacker could use an IDOR to gain access to a user’s profile information or reset a user’s password. In some cases, IDOR vulnerabilities can even be used to delete data or take control of the application.


Understanding access control and its vulnerabilities is paramount for securing web applications. Vertical and horizontal privilege escalation are common attack vectors with severe consequences. Implementing robust access control measures and regularly auditing your application’s security can help mitigate these risks and protect sensitive data.

Keep the bytes all Bytebusters!

BBX signing off.




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