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🛡️ Sentinel: [security improvement] #336

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🛡️ Sentinel: [security improvement] #336

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5 changes: 5 additions & 0 deletions .jules/sentinel.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
## 2024-06-30 - Replace dangerouslySetInnerHTML with Sandboxed iframe for Untrusted HTML

**Vulnerability:** Used `dangerouslySetInnerHTML` to render dynamic, untrusted email HTML within a React component.
**Learning:** Even when using a library like `DOMPurify` to sanitize HTML, rendering it directly into the main application document using `dangerouslySetInnerHTML` carries inherent risk. If the sanitizer fails to catch a novel exploit, is misconfigured, or if the sanitization rules change over time, the application is completely exposed to XSS, which can lead to session hijacking and unauthorized actions within the primary app context.
**Prevention:** For untrusted or dynamic HTML (like email previews), always use a sandboxed `iframe` with the `srcDoc` attribute to create an isolated browsing context. Apply `sandbox="allow-popups allow-popups-to-escape-sandbox"` to permit expected interactions (like clicking links) while omitting `allow-scripts` and `allow-same-origin`. Because the iframe is isolated, external CSS (like Tailwind classes) won't apply to its contents; any necessary styling must be explicitly injected via an inline `<style>` tag within the `srcDoc` string.
32 changes: 30 additions & 2 deletions components/accounts/ppp-savings-panel.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,29 @@ export function PppSavingsPanel({ orgSlug, accountId }: PppSavingsPanelProps) {
return `mailto:${encodeURIComponent(report.recipientEmail)}?subject=${encodeURIComponent(report.email.subject)}&body=${encodeURIComponent(draft)}`;
}, [draft, report]);
const sanitizedEmailHtml = useMemo(() => (report?.email.html ? DOMPurify.sanitize(report.email.html) : ""), [report]);
const previewHtml = useMemo(() => {
if (!sanitizedEmailHtml) return "";
return `
<!DOCTYPE html>
<html>
<head>
<style>
body {
font-family: ui-sans-serif, system-ui, sans-serif;
padding: 0;
margin: 0;
color: #000;
font-size: 0.875rem;
background: #fff;
}
</style>
</head>
<body>
${sanitizedEmailHtml}
</body>
</html>
`;
}, [sanitizedEmailHtml]);

const pdfHref = report ? `/api/runtime/organizations/${orgSlug}/accounts/${accountId}/ppp-savings/pdf?year=${report.year}` : null;

Expand Down Expand Up @@ -232,8 +255,13 @@ export function PppSavingsPanel({ orgSlug, accountId }: PppSavingsPanelProps) {
)}
</div>
</div>
<div className="min-h-[24rem] w-full overflow-auto bg-white p-6 text-sm text-black">
<div dangerouslySetInnerHTML={{ __html: sanitizedEmailHtml }} />
<div className="min-h-[24rem] w-full bg-white p-0">
<iframe
title="Email preview"
srcDoc={previewHtml}
className="h-full min-h-[24rem] w-full border-none p-6"
sandbox="allow-popups allow-popups-to-escape-sandbox"
/>
</div>
</div>
</div>
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1 change: 0 additions & 1 deletion package-lock.json
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