Cyberdudebivash

Broken Access Control (BAC) consistently tops the OWASP Top 10 list of web application security risks. It occurs when applications fail to properly enforce what authenticated users are allowed to do, enabling attackers to exploit flaws and gain unauthorized access to sensitive data, functions, or systems.

At CyberDudeBivash, we consider Broken Access Control a critical enterprise risk — one that can escalate into data breaches, privilege escalations, and compliance violations. In this article, we break down the attack mechanics, detection strategies, and mitigation techniques to help organizations build resilient defenses.

 How Broken Access Control Happens

1. Bypassing Authorization Checks
   • Attackers manipulate URLs, parameters, or tokens to access restricted pages.
   • Example: Changing /profile?user=123 to /profile?user=456 to view another user’s account.
2. Privilege Escalation
   • Exploiting flaws in role-based access control (RBAC).
   • Example: A normal user gains admin-level permissions through misconfigured roles.
3. Forced Browsing
   • Accessing hidden pages not linked in navigation (e.g., /admin or /backup).
4. JWT/Session Manipulation
   • Weak session tokens or flawed validation → attackers forge identities.

 Real-World Impact

• Data Breaches → Unauthorized access to personal records, financial data, or intellectual property.
• Account Takeovers (ATO) → Attackers escalate to privileged accounts.
• Compliance Failures → GDPR, HIPAA, PCI DSS violations due to unauthorized exposure.
• Supply Chain Compromise → Exploiting access gaps in APIs and microservices.

 Detection & Hunting Broken Access Control

Indicators of Exploitation

• Repeated 403/401 errors in logs (probing for access).
• Unusual account activities (normal users requesting admin endpoints).
• Brute force attempts on hidden endpoints (/admin, /config).

Threat Hunting Query Example (SIEM)

index=web_logs
| where (http_status=403 OR http_status=401) AND uri LIKE "%admin%"
| stats count by src_ip, uri, user

 Defense Strategies

1. Enforce Principle of Least Privilege (PoLP)
   • Assign users only the permissions they need.
   • Regularly review and prune excessive privileges.
2. Deny by Default
   • Access must be explicitly granted, not assumed.
3. Strong Role-Based / Attribute-Based Access Control (RBAC/ABAC)
   • Define granular rules at the API and application layers.
4. Centralized Access Control Mechanisms
   • Avoid scattered authorization checks in code → use a single, consistent enforcement layer.
5. Token Integrity Checks
   • Sign and validate JWTs/sessions with strong cryptography.
   • Reject expired or malformed tokens.
6. Security Testing & Automation
   • Perform penetration testing and fuzzing on access controls.
   • Use SAST/DAST tools integrated in CI/CD pipelines.

 MITRE ATT&CK Mapping

• T1078 – Valid Accounts: Exploiting mismanaged permissions.
• T1068 – Privilege Escalation: Gaining admin rights through access flaws.
• T1190 – Exploit Public-Facing Applications: Targeting APIs with broken access control.

 Lessons Learned

• Broken Access Control is not a bug, it’s a design flaw.
• Strong authentication is useless if authorization is weak.
• Continuous access reviews, automated testing, and centralized controls are critical to resilience.

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