T03 · Remote Payload Retrieval and Execution
Error
- Location
scripts/browser_tools.html:365- Finding
Unverified Remote JavaScript Executes with Access to User-Selected Files
- Content
View full analysis
``` The page also dynamically loads another executable dependency: ```javascript async function loadGifEnc() { return new Promise((resolve, reject) => { const script = document.createElement('script') script.src = 'https://cdn.jsdelivr.net/npm/gifenc@1.0.3/dist/gifenc.esm.min.js' script.onload = () => { window.GIFEncoder = window.GIFEnc.GIFEncoder window.quantize = window.GIFEnc.quantize window.applyPalette = window.GIFEnc.applyPalette resolve() } script.onerror = reject document.head.appendChild(script) }) } ``` ### Technical Analysis The browser tool loads and executes three JavaScript components directly from a third-party CDN. No Subresource Integrity hashes are specified, and the components are not distributed as reviewed local files. Although version strings are present in the URLs, the browser still trusts the response delivered by the CDN at runtime. If the CDN, package publisher, package artifact, DNS resolution, or delivery path is compromised, the returned JavaScript can differ from the code originally reviewed. These scripts execute in the same page context as the application code. They therefore have access to file objects, `FileReader` results, decoded image pixels, generated object URLs, and the document. The remote dependencies are necessary implementations of GIF and ZIP processing, but remote execution is not the minimum privilege required: the same libraries can be bundled locally. ### A ...[truncated 1184 chars]- Remediation
View remediation