Bypassing Content-Security-Policy leads to open-redirect and iframe xss

## Summary: `https://my.stripo.email/cabinet/#/template-editor/.....` has the ff: code to make iframes more secure: ```html <meta http-equiv="Content-Security-Policy" content="default-src 'self'; frame-src blocked: *.firebaseapp.com *.stripe.com *.google.com *.facebook.com 'self'; style-src 'self' 'unsafe-inline' *; script-src 'self' 'unsafe-eval' 'unsafe-inline' *.ampproject.org googletagmanager.com *.googletagmanager.com *.amplitude.com api.vk.com *.gstatic.com *.facebook.net *.google.com *.google-analytics.com *.stripe.com *.pingdom.net *.intercom.io *.intercomcdn.com *.stripo.email *.zscalertwo.net *.zscaler.com *.zscaler.net *.pinimg.com *.getsitecontrol.com; img-src 'self' blocked: *; connect-src 'self' *; child-src blob:; font-src 'self' *; object-src 'self' *"> ``` * <iframe> pointing to other domains won't work but, the whitelist in frame-src data has listed *.firebaseapp.com, a free hosting domain, leading to iframe abuse and redirects ## Steps To Reproduce: 1. Create a new message/template with HTML 2. Using nodeJS, deploy a page in firebaseapp. It's free. [Guide](https://firebase.google.com/docs/hosting/quickstart) 2. Mine is [hackerone-jm.firebaseapp.com](https://hackerone-jm.firebaseapp.com). Add the ff. line: `<iframe src="//hackerone-jm.firebaseapp.com"></iframe>` in the HTML editor 3. A browser popup will show, then redirect after ## Supporting Material/References: {F1268265} *Tested in Google Chrome Version 89.0.4389.128 (Official Build) (64-bit)* ## Impact * This can be used to launch a phishing attack against users of the same organization. * `viewstripo.email` is also vulnerable to this making it an open redirect/xss to all users. [POC](https://viewstripo.email/6a8ceb1a-7e45-4304-a93f-0cf4c32fc3111618586929192) * This also makes editing the message/template almost impossible without disabling javascript in your browser *this only works assuming the user has allowed `my.stripo.email` to redirect and spawn popups.*