1. Introduction
GraphQL Field Suggestions Detected is a vulnerability in GraphQL servers that allows attackers to discover schema information by exploiting a feature which suggests field names during query construction. This can lead to unauthorized access of sensitive data and potential arbitrary actions on the server. Systems running GraphQL APIs are typically affected, particularly those with default configurations or lacking strict input validation. Impact: Confidentiality – High, Integrity – Medium, Availability – Low.
2. Technical Explanation
GraphQL servers often include a feature to suggest field names when receiving incomplete queries. An attacker can send malformed requests and observe the suggestions to map out the entire GraphQL schema, including hidden or private endpoints. This is effectively a bruteforce attack on the API’s structure. The scanner detected that the remote GraphQL server has this suggestion feature enabled.
- Root cause: Enabled field suggestions in the GraphQL implementation.
- Exploit mechanism: An attacker sends requests with invalid field names and analyzes the suggestions returned by the server to discover available fields and types. For example, sending a query like “{ user { name” might return suggestions including “email”, “password”, etc., revealing hidden data.
- Scope: GraphQL servers running any implementation that provides field suggestions by default.
3. Detection and Assessment
To confirm vulnerability, check the server configuration or observe responses to malformed queries. A quick check involves examining the server settings for enabled features. Thorough assessment requires sending test requests with invalid fields.
- Quick checks: Check GraphQL server documentation for field suggestion options.
- Scanning: Burp Suite Intruder can be used to send a list of invalid field names and analyze responses for suggestions.
- Logs and evidence: Examine server logs for verbose error messages containing field name suggestions.
# No specific command available, requires interaction with the GraphQL endpoint.4. Solution / Remediation Steps
Disable the suggestion feature if possible in your GraphQL implementation. If disabling is not an option, consider using a different implementation that allows for this control.
4.1 Preparation
- Ensure you have access to the server’s configuration files or management interface. Rollback plan: Restore the previous configuration file if issues arise.
- Change windows may be needed depending on service criticality and impact of downtime. Approval from relevant IT teams may be required.
4.2 Implementation
- Step 1: Locate the GraphQL server’s configuration file (e.g., application.yml, settings.py).
- Step 2: Find the setting related to field suggestions or verbose error messages.
- Step 3: Disable the feature by setting the value to false or removing the relevant option.
- Step 4: Restart the GraphQL server for the changes to take effect.
4.3 Config or Code Example
Before
graphql:
enable-field-suggestions: trueAfter
graphql:
enable-field-suggestions: false4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this issue.
- Least privilege: Limit access to the GraphQL server and its data to only authorized users and services, reducing impact if exploited.
- Input validation: Validate all user inputs to ensure they conform to expected formats and values, preventing malicious queries.
4.5 Automation (Optional)
No automation is provided as the configuration varies significantly between GraphQL implementations.
5. Verification / Validation
Confirm the fix by sending a malformed query to the server and verifying that no field suggestions are returned. A simple service smoke test should ensure basic API functionality remains intact.
- Post-fix check: Send a query with an invalid field name (e.g., “{ user { nonExistentField” ) and confirm that the response does not include any field suggestions.
- Re-test: Repeat the scanning process from Section 3 to verify that no suggestions are now returned.
- Smoke test: Test a standard GraphQL query to ensure basic functionality is still working as expected (e.g., “{ user { name } }” ).
# No specific command available, requires interaction with the GraphQL endpoint. Expected output should not contain field suggestions.6. Preventive Measures and Monitoring
Update security baselines to include disabling field suggestions in GraphQL configurations. Implement CI/CD pipeline checks to enforce secure settings.
- Baselines: Update your security baseline or policy to require disabling field suggestions on all GraphQL servers.
- Pipelines: Add a check in your CI/CD pipeline to scan for enabled field suggestions during deployment.
- Asset and patch process: Regularly review and update the configuration of your GraphQL servers as part of your standard asset management process.
7. Risks, Side Effects, and Roll Back
Disabling field suggestions may make debugging more difficult for developers. If issues arise, restore the previous configuration.
- Risk or side effect 1: Disabling suggestions can reduce developer convenience during testing.
- Roll back: Restore the original GraphQL server configuration file and restart the service.
8. References and Resources
Links to resources related to this vulnerability.
- Vendor advisory or bulletin: https://blog.logrocket.com/security-and-performance-tips-and-tricks-for-your-graphql-servers/
- NVD or CVE entry: Not applicable, as this is a configuration issue rather than a specific vulnerability with a CVE ID.
- Product or platform documentation relevant to the fix: Consult your GraphQL server’s official documentation for instructions on disabling field suggestions.