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🛡️ Sentinel: [HIGH] Fix XSS vulnerability in WebView data transfer #147

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🛡️ Sentinel: [HIGH] Fix XSS vulnerability in WebView data transfer #147

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4 changes: 4 additions & 0 deletions .jules/sentinel.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
## 2024-05-01 - XSS in WebView
**Vulnerability:** Use of `injectJavaScript` to pass user-provided base64 images to WebView in `HomeScreen.tsx` and `ShiftScreen.tsx` introduces XSS risk.
**Learning:** React Native developers often use `injectJavaScript` with string interpolation for passing data, which can execute arbitrary JS if the string isn't sanitized perfectly. The memory correctly points out we should use `postMessage` instead.
**Prevention:** Avoid `injectJavaScript` for data transfer. Use `postMessage` from React Native to WebView, and set up a `message` listener inside the WebView's HTML string.
22 changes: 13 additions & 9 deletions src/screens/HomeScreen.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,17 @@ const HOME_REST_TIMING = { startHour: 12, startMinute: 0, endHour: 14, endMinute
const engineHtml = `<!DOCTYPE html><html lang="it"><head>
<script src="https://cdn.jsdelivr.net/npm/tesseract.js@5/dist/tesseract.min.js"></script></head>
<body style="background-color:transparent;"><script>
document.addEventListener("message", function(event) {
if (window.runTesseract && event.data) {
window.runTesseract(event.data);
}
});
window.addEventListener("message", function(event) {
if (window.runTesseract && event.data) {
window.runTesseract(event.data);
}
});

window.runTesseract = async function(base64JsonStr) {
try {
const images = JSON.parse(base64JsonStr);
Expand Down Expand Up @@ -283,15 +294,8 @@ export default function HomeScreen({ isFocused }: { isFocused?: boolean }) {
setProcessing(true); setOcrText('');
const base64List = result.assets.map(a => `data:image/jpeg;base64,${a.base64}`);
const base64Json = JSON.stringify(base64List);
// Use postMessage pattern to avoid script-injection risks with injectJavaScript
webViewRef.current?.injectJavaScript(`
if(window.runTesseract){
window.runTesseract(${JSON.stringify(base64Json)});
} else {
window.ReactNativeWebView.postMessage(JSON.stringify({success:false,error:'OCR non pronto'}));
}
true;
`);
// Use postMessage pattern to avoid script-injection risks with injectJavaScript
webViewRef.current?.postMessage(base64Json);
}
} catch (e) { if (__DEV__) console.error('[imagePicker]', e); setProcessing(false); }
};
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22 changes: 13 additions & 9 deletions src/screens/ShiftScreen.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -34,15 +34,8 @@ export default function ShiftScreen() {
const base64List = result.assets.map(a => `data:image/jpeg;base64,${a.base64}`);
const base64Json = JSON.stringify(base64List).replace(/'/g, "\\'");

const jsCode = `
if (window.runTesseract) {
window.runTesseract('${base64Json}');
} else {
window.ReactNativeWebView.postMessage(JSON.stringify({ success: false, error: "Motore OCR non pronto." }));
}
true;
`;
webViewRef.current?.injectJavaScript(jsCode);
// Use postMessage pattern to avoid script-injection risks with injectJavaScript
webViewRef.current?.postMessage(base64Json);
}
} catch (e) {
Alert.alert("Errore OCR", "Impossibile elaborare l'immagine.");
Expand Down Expand Up @@ -217,6 +210,17 @@ export default function ShiftScreen() {
</head>
<body style="background-color: transparent;">
<script>
document.addEventListener("message", function(event) {
if (window.runTesseract && event.data) {
window.runTesseract(event.data);
}
});
window.addEventListener("message", function(event) {
if (window.runTesseract && event.data) {
window.runTesseract(event.data);
}
});

window.runTesseract = async function(base64JsonStr) {
try {
const images = JSON.parse(base64JsonStr);
Expand Down
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