How Do APIs Get Hacked? A Developer & DevOps Perspective

APIs are now the most attacked layer in the application stack— APIs are being hit 68% more often per host than traditional web apps with APIs facing 1600% more DDoS traffic than web apps. This was found in the state of application security 2024 report where we analyzed 2 billion API attacks blocked on AppTrana WAAP.

This isn’t surprising. APIs are inherently automation-friendly, often underprotected, and expose direct access to data and logic. Most organizations rely on API gateways for routing and access control—but these alone offer limited defense against advanced threats like zero-day exploits, behavioral DDoS, or bot-based scraping.

This article breaks down how APIs get hacked, what kinds of vulnerabilities you should look out for, and what developers and DevOps teams can do to secure them—from code to runtime.

Why Attackers Love APIs

1. They Expose Business Logic — Without Frontend Controls

Unlike web UIs, APIs allow direct access to core workflows. With no client-side checks or UI boundaries, attackers can manipulate requests to bypass intended flows.

Real-World Abuse

POST /api/transfer
Authorization: Bearer <user-token>
Content-Type: application/json
{
"to_account": "123456789",
"amount": 10000
}

What Went Wrong: The backend didn’t revalidate business rules.

Dev Fix:

• Always validate input and enforce business logic server-side.
• Never trust frontend-enforced limits.

2. They Return Raw, Parsable Data — Perfect for Recon

APIs often return complete data objects with fields that shouldn’t be exposed publicly.

Example Response

{
"user_id": 92017,
"email": "admin@example.com",
"role": "admin",
"auth_token": "abc123",
"is_internal": true
}

What Went Wrong: Excessive data exposure. Sensitive fields like role and tokens should not be returned unless explicitly required.

Dev Fix:

• Use serializers to return only whitelisted fields per role/endpoint.
• Apply attribute-level access control.

3. They’re Built for Automation — and Abused That Way

Attackers love APIs because they can run thousands of automated requests without touching a browser.

Credential Stuffing via curl

for user in user1 user2 user3; do
curl -X POST https://api.example.com/login \
-H 'Content-Type: application/json' \
-d "{\"username\":\"$user\",\"password\":\"Password123\"}"
done

What Went Wrong: No rate limiting. No IP or user-level throttling.

Dev Fix:

• Apply behavior-based rate limits, IP bans, and CAPTCHA for abnormal login attempts.

4. They’re Often Poorly Documented or Forgotten

APIs evolve fast. Old or undocumented versions often remain live—and exploitable.

Zombie API Example

curl https://api.example.com/v1/export-all-users
What Went Wrong: No auth. No logging. Returns production data

Dev Fix:

• Implement lifecycle tagging and usage tracking
• Regularly scan for active endpoints
• Decommission old routes securely

Common API Vulnerabilities to Watch For (with Examples and Fixes)

1. Broken Object Level Authorization (BOLA)

APIs that use object identifiers in paths (`/api/user/123`) without checking ownership can be abused to access or modify other users’ data.

Exploit Example:

GET /api/user/9241/profile
Authorization: Bearer <token-of-user-A>

Fix:

• Always enforce access control per object at the backend.
• Never rely on frontend filtering or hidden fields.

# In your controller or handler
if user.id != requested_user_id:
return 403

Read our in-depth blog on BOLA and how to secure object-level access.

2. Broken Authentication

APIs that use hardcoded tokens, weak credential validation, or lack token expiration allow session hijacking and brute-force attacks.

Exploit Example:

curl -X POST https://api.example.com/login \
-d '{"username": "admin", "password": "guessme"}'

Fix:

• Use short-lived, signed tokens.
• Rotate secrets and keys.
• Implement account lockout and MFA.

Explore detailed strategies to fix broken authentication

3. Excessive Data Exposure

Developers often return full objects to clients, relying on the frontend to display only what’s necessary.

Exploit Example:

{
"user_id": 9001,
"email": "vip@example.com",
"credit_score": 810,
"is_internal": true
}

Fix:

Use serializers or DTOs to filter sensitive fields.

return {
"user_id": user.id,
"email": user.email
}

Read how to fix excessive data exposure in your APIs

4. Lack of Rate Limiting

OWASP Category: API4:2023

APIs that don’t throttle requests can be brute-forced, scraped, or used for DDoS.

Exploit Example:

for i in {1..10000}; do
curl -s https://api.example.com/login -d "{"username":"user$i","password":"123456"}"
done

Fix:

• Add rate limits.
• Use WAAP or API Gateway policies to throttle traffic.

Explore how to fix lack of rate limiting in your API setup

5. Injection Attacks

APIs that pass unsanitized inputs directly into queries are vulnerable to injection attacks.

Exploit Example:

GET /api/user?name=' OR 1=1 --

Fix:

• Use parameterized queries.
• Validate and sanitize input based on schema.

6. Mass Assignment

When APIs auto-map JSON payloads to objects without filtering, attackers can overwrite sensitive fields.

Exploit Example:

{
"username": "john",
"role": "admin",
"is_active": true
}

Fix:

Use allow-lists for input fields.

allowed_fields = ["username", "email"]
safe_data = {k: v for k, v in request.json.items() if k in allowed_fields}

7. Security Misconfiguration

Default error messages, exposed stack traces, insecure headers, and permissive CORS settings all expose APIs to risk.

Exploit Example:

Viewing full error stack via `/api/debug?trace=true` or accepting JWTs with `alg: none`

Fix:

• Disable debug and verbose logs in production.
• Configure CORS.
• Reject insecure JWTs.

Understand how to avoid security misconfigurations that expose your APIs.

8. Improper Asset Management

APIs that are no longer maintained or never documented often lack proper auth or security updates.

Exploit Example:

curl https://api.example.com/v1/export-users

Fix:

• Use automated discovery
• Maintain API inventory
• Deprecate and disable unused routes
• Apply the same security controls to non-production environments

How to Protect APIs from Hackers

1. Implement Strong Authentication and Authorization

• Use OAuth 2.0/OpenID Connect with short-lived access tokens
• Enforce multi-factor authentication for sensitive operations
• Validate object-level access (not just user roles)

Bad Example:

curl https://api.example.com/user?token=abc123
Good Example:

curl -H "Authorization: Bearer <jwt>" https://api.example.com/user/123

2. Validate Input and Enforce Schemas

• Reject payloads with unexpected or nested fields
• Use strict OpenAPI/JSON Schema validation at the gateway or backend
• Log and block mass assignment attempts

Payload Examples:

// Allowed fields
{ "email": "user@example.com", "password": "secret" }

// Rejected (extra fields)
{ "email": "user@example.com", "role": "admin", "status": "active" }

3. Apply Adaptive Rate Limiting and Bot Protection

• Block credential stuffing, scraping, and brute-force
• Use behavior- and context-based thresholds
• Combine IP, token, geo, and user-agent signals

4. Encrypt All Traffic and Protect Sensitive Data

• Enforce TLS 1.2+ with HSTS
• Mask or omit sensitive fields (e.g., tokens, roles) in API responses
• Apply data classification in payload filters

5. Discover and Monitor Shadow & Zombie APIs

• Use runtime discovery to map all external-facing APIs
• Flag APIs that are undocumented, outdated, or lack authentication
• Use WAAP or EASM tools to maintain live inventory and ownership tags

6. Enable Real-Time Vulnerability Remediation

Security scans (DAST, SAST, API fuzzing) are necessary—but they’re not enough if fixes take weeks or months.

What Happens Today:

• Vulnerabilities are found during quarterly scans or pentests
• Developers file Jira tickets
• Fixes are delayed due to prioritization, lack of context, or legacy code

What You Need:

• Autonomous remediation via WAAP: Block exploitation of known vulnerabilities in real time—without requiring code changes
• Fixes as policies: Virtual patches are deployed instantly for common API issues such as BOLA, mass assignment, or injection
• Feedback loop to DevSecOps: Security teams get alerts + context for permanent code fixes later

Example:

BOLA detected on `/api/orders/:id`.

WAAP blocks cross-user access immediately while ticketing system logs the violation with PII redacted for developers to fix in code.

Tools like SwyftComply help teams shrink remediation time from months to minutes, enabling compliance and reducing attack windows drastically.

7. Shift Security Left with CI/CD Integration

• Lint OpenAPI specs in pull requests
• Break builds if required fields or auth are missing
• Auto-generate negative test cases for business logic abuse
• Integrate with WAAP policies as code for seamless deployment

The Role of AppTrana WAAP in Securing APIs

Securing APIs goes beyond static scanning or gateway rules. AppTrana WAAP provides a full lifecycle approach to API security—from discovery to runtime protection:

1. API Discovery & Classification

AppTrana continuously analyzes traffic to identify all APIs—including shadow, orphaned, and third-party—and helps build a comprehensive API inventory. It classifies them by risk, ownership, and data sensitivity to give you complete visibility.

2. Continuous API Documentation

Automatically generates and updates OpenAPI specifications based on observed behavior, eliminating reliance on stale or incomplete manual docs.

3. Positive Security Model Automation

AppTrana learns expected behavior across endpoints and applies adaptive, allow-listed policies to block anomalies—without needing static rules.

4. API Vulnerability Scanning & Remediation

Scans APIs for OWASP Top 10 and business logic flaws. Detected vulnerabilities are patched instantly using virtual patches, while long-term fixes are routed to engineering with contextual evidence.

5. Behavioral DDoS & Bot Mitigation

AppTrana’s AI engine detects and mitigates volumetric, slow-rate, and behavior-based API abuse—including scraping and credential stuffing—while ensuring zero impact to legitimate users.

Unlike traditional gateways, AppTrana actively protects APIs in production and helps you remediate vulnerabilities in near real-time.

Final Words for Dev & DevOps Teams

APIs aren’t just integration tools—they’re high-value attack surfaces. As developers and DevOps professionals, you’re in a powerful position to prevent API attacks before they happen. By baking security into your API design, build, and deployment workflows, you can dramatically reduce the risk of breach—and eliminate the scramble of patching vulnerabilities in production.

Security doesn’t slow you down when it’s built into your process.

Want help discovering shadow APIs or protecting production APIs without rewriting code? Solutions like AppTrana WAAP and SwyftComply can help you detect, remediate, and protect—all in real-time.

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