Port 9222: reading a live browser session straight past MFA

The number reads like trivia and behaves like an unlocked side door. 9222 is a local TCP port, and the point is not the digits but what answers on it. A Chromium browser permits remote debugging through the --remote-debug-port command-line switch ^[6], and a client that connects gets the Chrome DevTools Protocol. The supplied documentation names that switch rather than pinning the port value, so treat 9222 as the signpost and hunt for any process listening on a debug port.

Once a client is on that interface, passwords stop mattering. The protocol's Network domain answers Network.getCookies with every browser cookie for the current URL, including detailed cookie data ^[1], and Network.setCookie writes cookies back and can overwrite existing ones ^[2]. A cookie with no expiry set is a session cookie ^[3]. Multi-factor authentication runs before that session cookie is issued; the cookie is the receipt proving the challenge already passed. Read it off a live, logged-in browser and you inherit the session without meeting the prompt. The Runtime domain compounds this, exposing remote JavaScript evaluation and letting a caller run function declarations inside the page's own execution context ^[4][5].

What moves it is configuration, not forensics afterward. In Edge, the RemoteDebuggingAllowed policy governs whether the switch works: enabled or unset permits remote debugging, disabled forbids it ^[6][7]. That control can be made mandatory but does not refresh dynamically, so it needs a browser restart to take hold, and it reaches Microsoft-account profiles ^[8]; it covers Edge 93 and later on Windows and macOS, with no support on Android or iOS ^[9]. Shorter server-enforced session limits cut how long a copied cookie stays live ^[11], and browser-level enrollment applies such policy without the user signing in ^[10].