T03 · Remote Payload Retrieval and Execution
Warning
- Location
references/html-template.md:12- Finding
Remote Third-Party JavaScript Is Executed Without Integrity Verification
- Content
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``` ### Technical Analysis Generated analytics reports load executable JavaScript from an external CDN whenever the report is opened. Although the URL specifies Chart.js version 4.4.1, the script element does not provide a Subresource Integrity hash or a restrictive Content Security Policy. Consequently, the effective JavaScript payload is not fully controlled by the audited project. If the CDN account, hosted asset, DNS resolution, TLS trust chain, or another delivery component is compromised, a modified response could execute arbitrary JavaScript in the report's browser context. This behavior also makes generated reports dependent on continued network access and the availability and trustworthiness of the external service. ### Attack Path 1. The Skill generates a report using `references/html-template.md`, or a user opens the included example report. 2. The browser requests Chart.js from `cdnjs.cloudflare.com`. 3. An attacker compromises or interferes with a component capable of controlling the returned CDN resource. 4. Because no integrity hash is specified, the browser accepts and executes the modified JavaScript. 5. The malicious script reads analytics data rendered in the document, changes displayed figures, or sends accessible report content to an attacker-controlled endpoint. ### Impact Assessment Exploitation grants JavaScript execution within the generated report's browser origin and context. A malicious dependency could: - Read business metrics and customer-derived aggregate data embedded in the report. - Falsify charts, recommendations, and operational conclusions. - Make arbitrary ou ...[truncated 334 chars]- Remediation
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``` 2. If CDN delivery must be retained, calculate and specify the exact Subresource Integrity hash: ```html ``` 3. Verify the hash against the exact reviewed Chart.js 4.4.1 artifact rather than copying a hash from an untrusted source. 4. Add a restrictive Content Security Policy that permits scripts only from approved sources and blocks unexpected outbound connections. Avoid allowing `unsafe-eval`. 5. Apply the same remediation to both `references/html-template.md` and `references/example-badminton.html`. 6. Consider self-hosting the referenced fonts as well, so reports can operate offline without disclosing connection metadata to third-party font services. ]]>