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Cake day: May 20th, 2024

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  • Netguard is a FOSS Android app which kinda works like a firewall. You can allow/block network access on a per-application basis. You can limit access e.g. on WiFi or on mobile etc. It also supports blocklists, supplementing your ad blocker.

    To the Android OS, Netguard acts as if it were a VPN.

    Limitations:

    • if you want to filter Android system services, you will break things. You will need to spend some time to do it right.
    • Chaining it to another VPN is only possible via SOCKS proxy
    • if you want to route some app’s traffic via VPN and others not, I think that is not possible. You could, however, manually turn off an app’s internet connection before disconnecting the VPN, if that is not too error-prone for you.

    The app is very stable, I have been using it for about 5 years without problems. For most use cases it is fire-and-forget, i.e. I rarely open the app any more.





  • If it is just the location, then it could be spoofed.

    If it is something that requires physical presence, then you need both devices to communicate with each other. If it is not done via QR code (like some online banking do), then both devices need to be connected, e.g. via WiFi or Bluetooth. In this case, if an attacker controls one of the devices (that’s the class of attacks 2FA should prevent you from), the attacker probably controls both devices. So what’s the point then?



  • How would MS Authenticator make it any better than TOTP?

    To break TOTP, the attacker would need to:

    a) be able to observe the initial exchange of the TOTP secrets. To do that, the attacker needs access to the victim’s computer (on user level) at that specific time they set up TOTP. TOTP is a TOFU concept and thus not designed to protect against that. However, if the attacker controls the victim’s computer at that time, the victim is screwed anyways even before setting up 2FA.

    b) have access to the TOTP app’s secret storage and to the victim’s login credentials (e.g. by phishing). If the attacker can gain that level of access, they would also have access to the Microsoft Authenticator’s secret storage, so there is no benefit of the Microsoft app.

    On the other hand, Microsoft Authenticator is a very huge app (>100MB is huge for an authenticator app, Aegis is just 6MB, FreeOTP+ 11MB), i.e. it brings a large attack surface, especially by connecting to the internet.

    I don’t think Microsoft Authenticator brings security benefits over a clean and simple TOTP implementation.