[maxloh]

Because a phone running an unknown OS is significantly more dangerous than a phone that hasn't received security updates for years. For example, a malicious OS maker could add their own certificate to the root store, essentially allowing them to MitM all the traffic you send to the bank.

Liability works on the principle that "if it's good enough for Google, it's good enough for me." A bank cannot realistically vet every vendor, so they rely on the OS maker to do the heavy lifting.

Even if they wanted to trust a third-party OS, they would need to review them on a case-by-case basis. A hobbyist OS compiled by a random volunteer would almost certainly be rejected.

[madeforhnyo]

I can add certificates on my unrooted android. That how HTTPToolkit [0] works, it only requires adb, which (thankfully) doesn't trip banking apps. Banking apps can (and do iirc) pin certificates, so a rooted phone adds no risk whatsoever.

Also in my experience a rooted phone experience is by far more secure than the OEM androids. Security is supposed to assess risk objectively, yet "running on a Xiaomi phone with 3rd party apps that cannot be uninstalled and have system access" is somehow more secure than "running on a signed LineageOS where user can edit hosts file".

[0] https://httptoolkit.com/

[Jean-Papoulos]

>Because a phone running an unknown OS is significantly more dangerous than a phone that hasn't received security updates for years.

That's just straight-up false ; the phone without security updates has known exploits its user knows nothing about (and certainly not how to avoid them). The phone with an unknown OS has a user capable of installing said OS, at the very least.

[protimewaster]

> Because a phone running an unknown OS is significantly more dangerous than a phone that hasn't received security updates for years.

I'm not convinced this is generally true, at least as can be detected by an app. Back when I had my phone rooted, it was configured so that it would pass all the Google checks and look like the stock OS. That configuration was probably dangerous, but apps were happy with it. Now that I run an OS that doesn't lie about what it is, I'm flagged as untrustworthy. What's the point in being honest?

Overall, I don't think they really have any idea what's a threat based on the checks they're doing, so I don't think they can say at all what's more or less trustworthy. But I think that a phone that reports being years out of date should reasonably not be expected to be secure, but yet they mark it as secure anyway. Many of those devices can be rooted in a way that can still pass their checks. I would think, if nothing else, that would be reason to block them, since they're interested in blocking rooted devices.