1. Introduction
ServiceNow Widgets Data Exposure is a vulnerability affecting custom JavaScript components within ServiceNow portal pages. It occurs when widget permissions are incorrectly configured, potentially allowing unauthenticated attackers to access sensitive information from the instance. This impacts confidentiality of data stored and processed by ServiceNow.
2. Technical Explanation
ServiceNow widgets use JavaScript code to define content on portal pages. Access control for these widgets is managed through fields set directly on the widget record, rather than relying on standard ServiceNow ACLs. If a widget’s permissions are not properly restricted, an attacker can remotely access data it shouldn’t. The Common Weakness Enumeration (CWE) identifiers associated with this issue are 16 and 200.
- Root cause: Incorrectly configured widget record permissions allowing public access or access by unintended roles.
- Exploit mechanism: An attacker sends a request to the ServiceNow instance, accessing a portal page containing a vulnerable widget. The widget executes with elevated privileges due to misconfigured ACLs, exposing sensitive data.
- Scope: Affects all ServiceNow instances using custom widgets where public access is enabled or incorrect roles are assigned.
3. Detection and Assessment
To confirm vulnerability, check widget permissions directly within the ServiceNow instance. A thorough assessment involves reviewing all custom widgets for potentially exposed data.
- Quick checks: Navigate to ‘System Definition > Widgets’ and review the ‘Public’ flag on each widget record.
- Scanning: There are no known specific signatures for this vulnerability; however, security scanners that identify misconfigured ACLs may provide some indication.
- Logs and evidence: Review ServiceNow system logs for unusual access patterns or data retrieval attempts related to portal pages.
Navigate to System Definition > Widgets in your ServiceNow instance.4. Solution / Remediation Steps
The following steps detail how to fix the issue of exposed widget data.
4.1 Preparation
- No services need to be stopped for this remediation.
4.2 Implementation
- Step 1: Disable the `public` flag on any widget record where public exposure is not intended.
- Step 2: Assign a specific role, that is *not* attributed to the `guest` user, to each ACL associated with the widget.
4.3 Config or Code Example
Before
Public: trueAfter
Public: false, Roles: 4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of issue.
- Practice 1: Least privilege – grant widgets only the minimum necessary permissions required for their function.
- Practice 2: Secure defaults – configure new widgets with restrictive access controls by default, rather than permissive settings.
4.5 Automation (Optional)
No automation is provided as changes are specific to each widget configuration and require careful review.
5. Verification / Validation
Confirm the fix by re-checking widget permissions and attempting to access data without appropriate credentials.
- Post-fix check: Navigate to ‘System Definition > Widgets’ and verify that the `public` flag is disabled for widgets where it should be.
- Re-test: Attempt to access a portal page containing the previously vulnerable widget as an unauthenticated user. Access should now be denied.
- Smoke test: Verify that authenticated users can still access the functionality provided by the widget with appropriate permissions.
- Monitoring: Monitor ServiceNow system logs for failed access attempts related to widgets, which could indicate ongoing exploitation attempts.
Navigate to System Definition > Widgets and confirm Public is set to false where expected.6. Preventive Measures and Monitoring
Implement security baselines and regular reviews of widget configurations.
- Baselines: Update your ServiceNow security baseline to include a requirement for restrictive widget permissions.
- Asset and patch process: Regularly review custom widgets and their associated access controls as part of a routine security assessment cycle.
7. Risks, Side Effects, and Roll Back
Disabling public access may break functionality for users who legitimately require it. Incorrect role assignments could also prevent authorized access.
- Risk or side effect 1: Disabling the `public` flag on a widget used by legitimate users will cause them to lose access.
- Risk or side effect 2: Assigning incorrect roles may restrict access for intended users.
- Roll back: Re-enable the ‘Public’ flag, or correct role assignments as needed.
8. References and Resources
- Vendor advisory or bulletin: https://www.enumerated.ie/index/servicenow-data-exposure