Attack Access Controls

Understanding and Answering Questions on Attack Access Controls - CEH Guide

Why Attack Access Controls are Important

Access control attacks target the mechanisms that enforce restrictions on what authenticated users can do. These attacks are critical to understand because:

• They can allow attackers to escalate privileges and access restricted areas of applications
• They often lead to unauthorized data exposure, modification, or deletion
• They exploit gaps between authentication (proving who you are) and authorization (what you're allowed to do)
• They can bypass business logic to perform unauthorized actions

What are Access Control Attacks?

Access control attacks focus on exploiting vulnerabilities in authorization mechanisms after authentication has occurred. While authentication verifies identity, access controls determine what resources an authenticated user can access and what actions they can perform.

Common types include:

• Vertical privilege escalation: Accessing functions or data reserved for higher privilege users
• Horizontal privilege escalation: Accessing resources belonging to other users at the same privilege level
• Parameter manipulation: Modifying request parameters to bypass access restrictions
• Forced browsing: Directly navigating to restricted pages by guessing URLs
• Insecure direct object references (IDOR): Accessing objects via references that lack proper verification

How Access Control Attacks Work

1. Authorization Bypass Techniques:
• URL parameter tampering (changing ID values in requests)
• Cookie manipulation to modify role information
• Modifying hidden form fields that contain access control data
• Session fixation to hijack privileged sessions

2. Common Vulnerabilities:
• Relying solely on client-side access controls (easily bypassed)
• Failing to verify resource ownership before granting access
• Insufficient session validation mechanisms
• Predictable resource locations or identifiers
• Improper enforcement of access controls at API endpoints

3. Attack Methodology:
• Mapping application functionality and identifying access points
• Identifying different user roles and permissions
• Testing parameters that may influence access decisions
• Attempting to access administrative functions
• Bypassing client-side restrictions using proxy tools

Exam Tips: Answering Questions on Attack Access Controls

Key Concepts to Master:
• Understand the difference between authentication and authorization
• Know the various access control models (MAC, DAC, RBAC, etc.)
• Recognize common access control implementation flaws
• Familiarize yourself with tools used for testing access controls (Burp Suite, OWASP ZAP)

Question Strategies:
• For scenario-based questions, identify what type of access control attack is being described
• Pay attention to clues about authentication state vs. authorization capabilities
• Look for details about request manipulation techniques in multiple-choice options
• When unsure, focus on the principles of least privilege and complete mediation

Common Question Themes:
• Identifying vulnerable code examples with access control flaws
• Describing attack methodologies for bypassing specific controls
• Selecting proper remediation techniques for access control vulnerabilities
• Understanding business impact of access control failures

Technical Details to Remember:
• Access controls should be enforced server-side, never rely on client-side alone
• Authorization checks should verify both resource ownership and action permission
• Sensitive operations require re-verification even after initial authentication
• JWT tokens, cookies, and hidden fields are common targets for access control attacks

In the CEH exam, access control questions often require you to analyze a scenario, identify the vulnerability pattern, and select the appropriate attack technique or defense. Focus on understanding the logical flow of authorization processes rather than just memorizing terms.