What are the top API security risks (OWASP API), and how do you prevent BOLA?
⚡ Short Answer
The #1 OWASP API risk is BOLA/IDOR — Broken Object Level Authorization: a user requests /orders/{id} for an id they don't own and the server returns it because it only checks authentication, not ownership. Prevent it by enforcing per-object authorization on every request, server-side.
☕Coffee Chat Question
Concept Made Simple
“What are the top API security risks (OWASP API), and how do you prevent BOLA?”
🧠Mind Map Answer
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🔥What If?
Think Beyond the Expected
Does using a random UUID instead of a sequential id fix BOLA?
No — that's security by obscurity. UUIDs are harder to guess but still leak (logs, referrals, shared links). The real fix is an authorization check: does THIS authenticated user have the right to THIS object? Enforce it on every read/write, never trust the id alone.
😂Real World
BOLA is the most common and damaging real-world API vulnerability (mass data exposure by iterating ids). The durable fix is centralized per-object authorization, often verified by automated tests that try cross-tenant access.
🎯Interviewer's Expectation
Keywords they're listening for:
⚠️Common Mistakes
- ✗Checking authentication but not ownership
- ✗Relying on unguessable ids for security
- ✗Returning full objects (excessive data exposure)
✅Best Practices
- ✓Enforce object-level authorization everywhere
- ✓Centralize authZ; test cross-tenant access
- ✓Return only needed fields (DTOs)
🔁Follow-up Questions
- 1Why is UUID not an authorization control?
- 2How do you test for BOLA automatically?
- 3What are excessive data exposure and mass assignment?
🧩Related Technologies
📚References
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Plain-language foundations
I'm preparing for a software engineering interview and want to understand this from scratch, as a beginner. Topic: Auth (REST APIs) Interview question: "What are the top API security risks (OWASP API), and how do you prevent BOLA?" Please: 1. Explain the core idea in simple, plain language, using an everyday analogy. 2. Define any technical terms you use. 3. Walk through one small, concrete example. 4. Finish with a single sentence I can easily remember. Keep the tone friendly and assume I'm new to this topic.
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