GHSA-p2jh-44qj-pf2v Exfiltration of hashed SMB credentials on Windows via file:// redirect

• npm electron: < 18.3.7 → fixed in 18.3.7 • npm electron: >= 20.0.0-beta.1, < 20.0.1 → fixed in 20.0.1 • npm electron: >= 19.0.0-beta.1, < 19.0.11 → fixed in 19.0.11

Impact When following a redirect, Electron delays a check for redirecting to file:// URLs from other schemes. The contents of the file is not available to the renderer following the redirect, but if the redirect target is a SMB URL such as `file://some.website.com/`, then in some cases, Windows will connect to that server and attempt NTLM authentication, which can include sending hashed credentials. Patches This issue has been fixed in all current stable versions of Electron. Specifically, these versions contain the fixes: • 21.0.0-beta.1 • 20.0.1 • 19.0.11 • 18.3.7 We recommend all apps upgrade to the latest stable version of Electron. Workarounds If upgrading isn't possible, this issue can be addressed without upgrading by preventing redirects to file:// URLs in the `WebContents.on('will-redirect')` event, for all WebContents: ```js app.on('web-contents-created', (e, webContents) => { webContents.on('will-redirect', (e, url) => { if (/^file:/.test(url)) e.preventDefault() }) }) ``` For more information If you have any questions or comments about this advisory, email us at [email protected]. Credit Thanks to user @coolcoolnoworries for reporting this issue.