08 Мар, 2024

Server Side Vulnerability Horizontal Privilege Escalation

In field of cybersecurity, ethical hacking, ПЕНТЕСТ and cloud pentest. A security problem known as a server-side vulnerability linked to horizontal privilege escalation occurs when an attacker obtains unauthorized access to features or data that are owned by a different user who has the same degree of privileges. In contrast to vertical privilege escalation, which aims to elevate an attacker’s privileges (from regular user to administrator, for example), horizontal privilege escalation involves an attacker using vulnerabilities to act or access data as a different user without raising their own privilege level.

Example of exploitation

In this example web site has a horizontal privilege escalation vulnerability on the user account page
The username of account is – <Carlos> First we need to find a blog post that was posted by Carlos
After we need to click on <Carlos> and observe the URL contains his user ID – Note his ID
Then we log in to the out account and we will change our ID parameter to saved user
And retrieve and submit API key

First step we log in to our account we need to understand how request ID look like 

So on that screenshot we can see users ID
Our goal is to find users <carlos> ID

Here we can see user <carlos> post  we need to click on it , and find that request in Burp

We need to copy user ID <01ee2759-e50c-4ce4-9262-f3f1220a5e7a>

We go back to our request from our account and send it to repeater 

We replace our ID to users ID

We click on send button and in the response we can see that our username is Carlos ! And also we have Api key that we need to pass our mission 


we successfully pass the lab !

Automated Scanners and manual tools

Automated Scanners

1. OWASP ZAP (Zed Attack Proxy): An open-source web application security scanner that can help identify security vulnerabilities in web applications. It includes various tools and scanners, including ones for session management and authentication flaws.

2. Burp Suite: Offers both free and professional versions and is widely used for security testing of web applications. It can identify session management issues and potentially insecure direct object references (IDORs) which can lead to horizontal privilege escalation.

3. Acunetix: A fully automated web vulnerability scanner that checks and detects a wide range of vulnerabilities, including IDOR and other access control issues.

4. Netsparker: An automated scanner that can identify vulnerabilities like IDOR and insufficient access controls in web applications.

Although these automated technologies are capable of detecting possible vulnerabilities, they may not always detect or validate horizontal privilege escalation in the absence of human verification.

Manual Testing Tools and Techniques

1. Proxy Tools (e.g., Burp Suite, OWASP ZAP): By acting as a man-in-the-middle proxy, these tools allow security researchers to intercept and modify requests sent from the client to the server and vice versa. This is critical for testing how an application responds to manipulated requests mimicking unauthorized access attempts.

2. Custom Scripts: Writing custom scripts (in languages such as Python) using libraries like requests or Selenium can help automate specific tests for horizontal privilege escalation, especially when testing complex scenarios or large numbers of user roles and permissions.

3. Access Control Testing: Methodically testing each feature of the application, ensuring that one user cannot access or modify another user’s data or execute actions on their behalf without proper authorization.

4. Session Management Testing: Manually testing the application’s session management by attempting to switch sessions, hijack sessions, or exploit session fixation vulnerabilities to gain unauthorized access.

Average CVSS score

Horizontal privilege escalation vulnerabilities, which give attackers access to or alteration of other users’ data without the necessary authorization, frequently have a medium to high impact on confidentiality, integrity, or availability. The average CVSS score, however, can vary substantially because to the wide variation in the precise features of these vulnerabilities. Such vulnerabilities, depending on the details of the access control weakness and the value of the data or functionality that could be compromised, generally fall into the medium to high severity category (CVSS scores of 4.0 to 8.9). Every vulnerability needs to be examined separately for the most accurate assessment, taking into account the particulars of the application and the data it manages. Since the impact and exploitability of horizontal privilege escalation might differ significantly amongst applications, there is no one-size-fits-all CVSS score.

CVES related to horizontal privilege escalation

Horizontal privilege escalation CVEs often describe circumstances in which an attacker can act as another user, view or edit another user’s data, or operate at a level of privilege that should only be available to the legitimate user. These flaws are present in a variety of software, including OS systems and web apps, and they are frequently caused by improper session management, insufficient access constraints, or insecure direct object references (IDOR).

1. Search the National Vulnerability Database (NVD): Use keywords like “horizontal privilege escalation”, “inadequate access controls”, “IDOR”, or “insecure direct object references” at NVD.

2. CVE Details: A searchable database where you can use similar keywords to find vulnerabilities related to horizontal privilege escalation.

3 Security Advisory Pages: Many vendors maintain security advisories or bulletins that detail known vulnerabilities, including those that might allow for horizontal privilege escalation. Searching these pages with related keywords can yield specific CVEs.

Checklist related to horizontal privilege escalation

Design and Architecture Review

1. Define Clear Access Control Requirements: Ensure that the application’s access control requirements are clearly defined, including roles, permissions, and the distinction between user types.

2. Principle of Least Privilege: Design the system so that users are granted the minimum levels of access – or permissions – needed to perform their functions.

3. Use Role-Based Access Control (RBAC): Implement RBAC to manage access to resources based on roles.

4. Secure Session Management: Design secure session management practices, ensuring that session tokens are properly protected and invalidated upon logout or expiration.


5. Parameterized Queries: Use parameterized queries to prevent SQL injection, which could be exploited to achieve privilege escalation.

6. Secure Direct Object References: Avoid using direct object references that users can manipulate. Use indirect references mapped server-side instead.

7. Implement Strong Authentication and Authorization Checks: Ensure that every sensitive function or endpoint performs authentication and authorization checks.

8. Encrypt Sensitive Data: Ensure that sensitive data is encrypted both in transit and at rest to prevent unauthorized access.

Code Review and Testing

9. Static Code Analysis: Use static application security testing (SAST) tools to identify insecure coding patterns that might lead to privilege escalation.

10. Dynamic Analysis: Use dynamic application security testing (DAST) tools to identify vulnerabilities that could be exploited for privilege escalation in a running application.

11. Manual Testing and Review: Conduct thorough manual reviews and tests, focusing on authentication, session management, and access control functionalities.

12. Penetration Testing: Perform regular penetration tests to identify and mitigate possible exploitation scenarios for horizontal privilege escalation.

Deployment and Monitoring

13. Regular Updates and Patch Management: Keep all systems and software up to date with the latest patches to mitigate known vulnerabilities.

14. Logging and Monitoring: Implement detailed logging and monitoring of access and actions. This can help in detecting and investigating suspicious activities that may indicate attempts at privilege escalation.

15. Incident Response Plan: Have an incident response plan in place that includes procedures for dealing with unauthorized access or potential privilege escalation incidents.

16. User Training and Awareness: Educate users about security best practices, phishing, and social engineering attacks that could lead to unauthorized access.

Regular Security Assessments

17. Vulnerability Scanning: Regularly perform vulnerability scanning to detect new threats or missed vulnerabilities.

18. Security Audits: Conduct periodic security audits to assess the effectiveness of the access control mechanisms and to ensure compliance with security policies.

Books and courses


1. The Web Application Hacker’s Handbook: Finding and Exploiting Security Flaws by Dafydd Stuttard and Marcus Pinto: This book provides extensive coverage of web application security, including topics on access control vulnerabilities and how to identify and exploit them.

2. OWASP Testing Guide v4: While not a book you can buy, this free resource from the Open Web Application Security Project (OWASP) is a comprehensive guide to testing the security of web applications, including tests for broken access control.

3. Hacking: The Art of Exploitation, 2nd Edition by Jon Erickson: Although not specifically focused on web applications, this book offers a deep dive into the mindset and techniques used by hackers, which can be invaluable in understanding how vulnerabilities like horizontal privilege escalation can be exploited.

4. Black Hat Python: Python Programming for Hackers and Pentesters by Justin Seitz: This book introduces Python programming for security professionals, including how to write scripts to automate the exploitation of security vulnerabilities, potentially including those related to access control.


1. Web Application Penetration Testing by Offensive Security : This course covers various aspects of web application security, including identifying and exploiting access control flaws.

2. Coursera – Web Application Security specialization: Various courses within this specialization tackle web security issues, including broken access controls, and provide hands-on experiences.

3. Advanced Web Attacks and Exploitation by Offensive Security (AWAE): This advanced course goes deeper into the exploitation of web applications, including sophisticated access control issues.

4. Udemy courses on web security: Search for courses related to web application security or ethical hacking that cover access control vulnerabilities. There are several highly rated courses by experienced security professionals.

Additional Resources

OWASP Resources: The OWASP website offers various resources, including documentation, tools, and community contributions on broken access control and other security vulnerabilities.

Capture The Flag (CTF) Challenges and Hack The Box: Engaging in CTF challenges or platforms like Hack The Box can provide practical experience in identifying and exploiting security vulnerabilities, including broken access control.


A serious security issue in online applications is horizontal privilege escalation, which gives attackers the ability to get around access constraints and perform operations or access data as another user without the necessary authorization. The integrity, confidentiality, and accessibility of sensitive data and system resources may be jeopardized as a result of this vulnerability, which can also result in data tampering and unauthorized disclosure. In summary, even though horizontal privilege escalation is a major risk to web application security, by being aware of its workings and possible effects, businesses can take preventative measures to safeguard their apps against unwanted access. Organizations can greatly lower the risk of horizontal privilege escalation and other security vulnerabilities by integrating security into the core of the application development and deployment process and encouraging a culture of security awareness.

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