Make the Android pages more consistent (#1086)

Co-authored-by: Jonah Aragon <jonah@triplebit.net>
Signed-off-by: Daniel Gray <dng@disroot.org>
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Tommy 2022-04-24 15:16:26 +00:00 committed by Daniel Gray
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@ -6,17 +6,25 @@ icon: 'material/cellphone-cog'
CalyxOS includes a device controller app so there is no need to install a third party app like Shelter.
GrapheneOS extends the user profile feature allowing a user to press an "End Session" button. This button clears the encryption key from memory. There are plans to add a [cross profile notifications system](https://github.com/GrapheneOS/os-issue-tracker/issues/88) in the future. GrapheneOS plans to introduce nested profile support with better isolation in the future.
GrapheneOS extends the user profile feature, allowing you to end a current session. To do this, select *End Session* which will clear the encryption key from memory. There are plans to add a [cross profile notifications system](https://github.com/GrapheneOS/os-issue-tracker/issues/88) in the future. GrapheneOS plans to introduce nested profile support with better isolation in the future.
## Sandboxed Google Play vs Privileged MicroG
## Sandboxed Google Play vs Privileged microG
When Google Play services are used on GrapheneOS, they run as a user app and are contained within a user or work profile.
Sandboxed Google Play is confined using the highly restrictive, default [`untrusted_app`](https://source.android.com/security/selinux/concepts) domain provided by [SELinux](https://en.wikipedia.org/wiki/Security-Enhanced_Linux). Permissions for apps to use Google Play Services can be revoked at any time by the user.
MicroG is a reimplementation of Google Play Services. This means it needs to be updated every time Android has a major version update (or the Android API changes). It also needs to run in the highly privileged [`system_app`](https://source.android.com/security/selinux/concepts) SELinux domain like normal Google Play Services and requires access to [signature spoofing](https://madaidans-insecurities.github.io/android.html#microg-signature-spoofing) so this is less secure than the Sandboxed Google Play approach. We do not believe MicroG provides any privacy advantages over Sandboxed Google Play except for the option to *shift trust* of the location backend from Google to another provider such as Mozilla or DejaVu.
microG is an open-source re-implementation of Google Play Services. This means it needs to be updated every time Android has a major version update (or the Android API changes). It also needs to run in the highly privileged [`system_app`](https://source.android.com/security/selinux/concepts) SELinux domain like regular Google Play Services, and it requires an operating system that allows [signature spoofing](https://github.com/microg/GmsCore/wiki/Signature-Spoofing), which allows system apps to insecurely masquerade as other apps. This is less secure than Sandboxed Google Play's approach, which does not need access to sensitive system APIs.
From a usability point of view, Sandboxed Google Play also works well with far more applications than MicroG, thanks to its support for services like [Google Play Games](https://play.google.com/googleplaygames) and [In-app Billing API](https://android-doc.github.io/google/play/billing/api.html).
When using Sandboxed Play Services, you have the option to reroute location requests to the Play Services API back to the OS location API which uses satellite based location services. With microG, you have the option to either not use a network location backend at all, *shift trust* to another location backend like Mozilla, or use [DejaVu](https://github.com/n76/DejaVu), a location backend that locally collects and saves RF-based location data to an offline database which can be used when GPS is not available.
Network location providers like Play Services or Mozilla rely the on the MAC addresses of surrounding WiFi access points and Bluetooth devices being submitted for location approximation. Choosing a network location like Mozilla to use with microG provides little to no privacy benefit over Google because you are still submitting the same data and trusting them to not profile you.
Local RF location backends like DejaVu require that the phone has a working GPS first for the local RF data collected to be useful. This makes them ineffective as location providers, as the job of a location provider is to assist location approximation when satellite based services are not working.
If your threat model requires protecting your location or the MAC addresses of nearby devices, rerouting location requests to the OS location API is probably the best option. The benefit brought by microG's custom location backend is minimal at best when compared to Sandboxed Play Services.
In terms of application compatibility, Sandboxed Google Play outperforms microG due to its support for many services which microG has not yet implemented, like [Google Play Games](https://play.google.com/googleplaygames) and [In-app Billing API](https://android-doc.github.io/google/play/billing/api.html). Authentication using [FIDO](security/multi-factor-authentication#fido-fast-identity-online) with online services on Android also relies on Play Services, and the feature is not yet implemented in microG.
## Privileged App Extensions

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@ -6,17 +6,17 @@ Android is a secure operating system that has strong [app sandboxing](https://so
## Choosing an Android Distribution
When you buy an Android phone, the device's default operating system often comes with invasive integration with apps and services which are not part of the [Android Open Source Project](https://source.android.com/). An example of such is Google Play Services, which has unrevokable privileges to access your files, contacts storage, call logs, SMS messages, location, camera, microphone, hardware identifiers, and so on. These apps and services increase the attack surface of your device and are the source of various privacy concerns with Android.
When you buy an Android phone, the device's default operating system often comes with invasive integration with apps and services that are not part of the [Android Open Source Project](https://source.android.com/). An example of such is Google Play Services, which has unrevokable privileges to access your files, contacts storage, call logs, SMS messages, location, camera, microphone, hardware identifiers, and so on. These apps and services increase the attack surface of your device and are the source of various privacy concerns with Android.
This problem could be solved by using a custom Android distribution that does not come with such invasive integration. Unfortunately, many custom Android distributions often break the Android security model by not supporting critical security features such as AVB, rollback protection, firmware updates, and so on. Some distributions also ship with [`userdebug`](https://source.android.com/setup/build/building#choose-a-target) builds which expose root via the [Android Debug Bridge](https://developer.android.com/studio/command-line/adb) (ADB) and requires [more permissive](https://github.com/LineageOS/android_system_sepolicy/search?q=userdebug&type=code) SELinux policies to accomodate debugging features, resulting in a further increased attack surface and weakened security model.
This problem could be solved by using a custom Android distribution that does not come with such invasive integration. Unfortunately, many custom Android distributions often violate the Android security model by not supporting critical security features such as AVB, rollback protection, firmware updates, and so on. Some distributions also ship [`userdebug`](https://source.android.com/setup/build/building#choose-a-target) builds which expose root via [ADB](https://developer.android.com/studio/command-line/adb) and require [more permissive](https://github.com/LineageOS/android_system_sepolicy/search?q=userdebug&type=code) SELinux policies to accomodate debugging features, resulting in a further increased attack surface and weakened security model.
Ideally, when choosing a custom Android distribution, you should make sure that it upholds the Android security model. At the very least, the distribution should have production builds, support for AVB, rollback protection, timely firmware and operating system updates, and SELinux in enforcing mode. All of our recommended Android distributions satisfy these criteria.
Ideally, when choosing a custom Android distribution, you should make sure that it upholds the Android security model. At the very least, the distribution should have production builds, support for AVB, rollback protection, timely firmware and operating system updates, and SELinux in [enforcing mode](https://source.android.com/security/selinux/concepts#enforcement_levels). All of our recommended Android distributions satisfy these criteria.
[Our Android System Recommendations :material-arrow-right:](../android.md){ .md-button }
## Avoid Root
## Avoid Rooting
[Rooting](https://en.wikipedia.org/wiki/Rooting_(Android)) Android phones can decrease security significantly as it weakens the complete [Android security model](https://en.wikipedia.org/wiki/Android_(operating_system)#Security_and_privacy). This can decrease privacy should there be an exploit that is assisted by the decreased security. Common rooting methods involve directly tampering with the boot partition, making it impossible to perform successful Verified Boot. Apps that require root will also modify the system partition meaning that Verified Boot would have to remain disabled. Having root exposed directly in the user interface also increases the attack surface of your device and may assist in [privilege escalation](https://en.wikipedia.org/wiki/Privilege_escalation) vulnerabilities and [SELinux](https://en.wikipedia.org/wiki/Security-Enhanced_Linux) policy bypasses.
[Rooting](https://en.wikipedia.org/wiki/Rooting_(Android)) Android phones can decrease security significantly as it weakens the complete [Android security model](https://en.wikipedia.org/wiki/Android_(operating_system)#Security_and_privacy). This can decrease privacy should there be an exploit that is assisted by the decreased security. Common rooting methods involve directly tampering with the boot partition, making it impossible to perform successful Verified Boot. Apps that require root will also modify the system partition meaning that Verified Boot would have to remain disabled. Having root exposed directly in the user interface also increases the [attack surface](https://en.wikipedia.org/wiki/Attack_surface) of your device and may assist in [privilege escalation](https://en.wikipedia.org/wiki/Privilege_escalation) vulnerabilities and SELinux policy bypasses.
Adblockers which modify the [hosts file](https://en.wikipedia.org/wiki/Hosts_(file)) (AdAway) and firewalls (AFWall+) which require root access persistently are dangerous and should not be used. They are also not the correct way to solve their intended purposes. For Adblocking we suggest encrypted [DNS](../dns.md) or [VPN](../vpn.md) server blocking solutions instead. RethinkDNS, TrackerControl and AdAway in non-root mode will take up the VPN slot (by using a local loopback VPN) preventing you from using privacy enhancing services such as Orbot or a real VPN server.
@ -24,13 +24,23 @@ AFWall+ works based on the [packet filtering](https://en.wikipedia.org/wiki/Fire
We do not believe that the security sacrifices made by rooting a phone are worth the questionable privacy benefits of those apps.
## Verified Boot
[Verified Boot](https://source.android.com/security/verifiedboot) is an important part of the Android security model. It provides protection against [evil maid](https://en.wikipedia.org/wiki/Evil_maid_attack) attacks, malware persistence, and ensures security updates cannot be downgraded with [rollback protection](https://source.android.com/security/verifiedboot/verified-boot#rollback-protection).
Android 10 and above has moved away from full-disk encryption to more flexible [file-based encryption](https://source.android.com/security/encryption/file-based). Each user's data is encrypted using their own unique encryption key, and the operating system files are left unencrypted.
Verified Boot ensures the integrity of the operating system files, thereby preventing an adversary with physical access from tampering or installing malware on the device. In the unlikely case that malware is able to exploit other parts of the system and gain higher privileged access, Verified Boot will prevent and revert changes to the system partition upon rebooting device.
Unfortunately, OEMs are only obliged to support Verified Boot on their stock Android distribution. Only a few OEMs such as Google support custom AVB key enrollment on their devices. Additionally, some AOSP derivatives such as LineageOS or /e/ OS do not support Verified Boot even on hardware with Verified Boot support for third party operating systems. We recommend that you check for support **before** purchasing a new device. AOSP derivatives which do not support Verified Boot are **not** recommended.
## Firmware Updates
Firmware updates are critical for maintaining security and without them your device cannot be secure. OEMs have support agreements with their partners to provide the closed source components for a limited support period. These are detailed in the monthly [Android Security Bulletins](https://source.android.com/security/bulletin).
As the components of the phone such as the processor and radio technologies rely on closed source components, the updates must be provided by the respective manufacturers. Therefore it is important that you purchase a device within an active support cycle. [Qualcomm](https://www.qualcomm.com/news/releases/2020/12/16/qualcomm-and-google-announce-collaboration-extend-android-os-support-and) and [Samsung](https://news.samsung.com/us/samsung-galaxy-security-extending-updates-knox/) support their devices for 4 years while cheaper products often have shorter support. With the introduction of the [Pixel 6](https://support.google.com/pixelphone/answer/4457705), Google now makes their own system on chip (SoC) and they will provide 5 years of support.
As the components of the phone such as the processor and radio technologies rely on closed source components, the updates must be provided by the respective manufacturers. Therefore it is important that you purchase a device within an active support cycle. [Qualcomm](https://www.qualcomm.com/news/releases/2020/12/16/qualcomm-and-google-announce-collaboration-extend-android-os-support-and) and [Samsung](https://news.samsung.com/us/samsung-galaxy-security-extending-updates-knox/) support their devices for 4 years, while cheaper products often have shorter support cycles. With the introduction of the [Pixel 6](https://support.google.com/pixelphone/answer/4457705), Google now makes their own SoC and they will provide a minimum of 5 years of support.
Devices that have reached their end-of-life (EoL) and are no longer supported by the SoC manufacturer, cannot receive firmware updates from OEM vendors or after market Android distributors. This means that security issues with those devices will remain unfixed.
EOL devices which are no longer supported by the SoC manufacturer cannot receive firmware updates from OEM vendors or after market Android distributors. This means that security issues with those devices will remain unfixed.
## Android Versions
@ -44,7 +54,7 @@ Should you want to run an app that you're unsure about, consider using a user or
## User Profiles
Multiple user profiles (Settings → System → Multiple users) are the simplest way to isolate in Android. With user profiles you can limit a user from making calls, SMS or installing apps on the device. Each profile is encrypted using its own encryption key and cannot access the data of any other profiles. Even the device owner cannot view the data of other profiles without knowing their password. Multiple user profiles is a more secure method of isolation.
Multiple user profiles can be found in **Settings****System****Multiple users** and are the simplest way to isolate in Android. With user profiles you can limit a user from making calls, SMS or installing apps on the device. Each profile is encrypted using its own encryption key and cannot access the data of any other profiles. Even the device owner cannot view the data of other profiles without knowing their password. Multiple user profiles is a more secure method of isolation.
## Work Profile
@ -56,19 +66,9 @@ The work profile is dependent on a device controller to function. Features such
This method is generally less secure than a secondary user profile; however, it does allow you the convenience of running apps in both the work and personal profiles simultaneously.
## Verified Boot
[Verified Boot](https://source.android.com/security/verifiedboot) is an important part of the Android security model. It provides protection against [evil maid](https://en.wikipedia.org/wiki/Evil_maid_attack) attacks, malware persistence, and ensures security updates cannot be downgraded with [rollback protection](https://source.android.com/security/verifiedboot/verified-boot#rollback-protection).
Android 10 and above has moved away from full-disk encryption to more flexible [file-based encryption](https://source.android.com/security/encryption/file-based).
Each user's data is encrypted using their own unique encryption key, and the operating system files are left unencrypted. Verified Boot ensures the integrity of the operating system files preventing an adversary with physical access from tampering or installing malware on the device. In the unlikely case that malware is able to exploit other parts of the system and gain higher privileged access, Verified Boot will prevent and revert changes to the system partition upon reboot of the device.
Unfortunately, OEMs are only obliged to support Verified Boot on their stock Android distribution. Only a few OEMs such as Google support custom AVB key enrollment on their devices. Some AOSP derivatives such as LineageOS or /e/ OS do not support Verified Boot even on hardware with Verified Boot support for third party operating systems. We recommend that you check for support **before** purchasing a new device. AOSP derivatives which do not support Verified Boot are **not** recommended.
## VPN Killswitch
Android 7 and above supports a VPN killswitch and it is available without the need to install third party apps. This feature can prevent leaks if the VPN is disconnected. It can be found in :gear: Settings → Network & internet → VPN → :gear: → Block connections without VPN.
Android 7 and above supports a VPN killswitch and it is available without the need to install third party apps. This feature can prevent leaks if the VPN is disconnected. It can be found in (:gear: **Settings****Network & internet****VPN** → :gear: → **Block connections without VPN**).
## Global Toggles
@ -80,7 +80,7 @@ If you are using a device with Google services, either your stock operating syst
### Advanced Protection Program
If you have a Google account we suggest enrolling in the [Advanced Protection Program](https://landing.google.com/advancedprotection/). It is available at no cost to anyone with two or more hardware security keys with [FIDO](/security/multi-factor-authentication.md#fido-fast-identity-online) support.
If you have a Google account we suggest enrolling in the [Advanced Protection Program](https://landing.google.com/advancedprotection/). It is available at no cost to anyone with two or more hardware security keys with [FIDO](../security/multi-factor-authentication.md#fido-fast-identity-online) support.
The Advanced Protection Program provides enhanced threat monitoring and enables:
@ -96,18 +96,24 @@ The Advanced Protection Program provides enhanced threat monitoring and enables:
- Mandatory automatic device scanning with [Play Protect](https://support.google.com/googleplay/answer/2812853?hl=en#zippy=%2Chow-malware-protection-works%2Chow-privacy-alerts-work)
- Warning the user about unverified applications
### Google Play System Updates
In the past, Android security updates had to be shipped by the operating system vendor. Android has become more modular beginning with Android 10, and Google can push security updates for **some** system components via the privileged Play Services.
If you have an EOL device shipped with Android 10 or above and are unable to run any of our recommended operating systems on your device, you are likely going to be better off sticking with your OEM Android installation (as opposed to an operating system not listed here such as LineageOS or /e/ OS). This will allow you to receive **some** security fixes from Google, while not violating the Android security model by using an insecure Android derivative and increasing your attack surface. We would still recommend upgrading to a supported device as soon as possible.
### Advertising ID
All devices with Google Play Services installed automatically generate an [advertising ID](https://support.google.com/googleplay/android-developer/answer/6048248?hl=en) used for targeted advertising. Disable this feature to limit the data collected about you.
On Android distributions with [Sandboxed Google Play](https://grapheneos.org/usage#sandboxed-google-play), go to :gear: Settings → Apps → Sandboxed Google Play → Google Settings → Ads and select **Delete advertising ID**.
On Android distributions with [Sandboxed Google Play](https://grapheneos.org/usage#sandboxed-google-play), go to :gear: **Settings****Apps****Sandboxed Google Play****Google Settings****Ads**, and select *Delete advertising ID*.
On Android distributions with privileged Google Play Services (such as stock OSes), the setting may be in one of several locations. Check
- :gear: Settings → Google → Ads
- :gear: Settings → Privacy → Ads
- :gear: **Settings****Google** → **Ads**
- :gear: **Settings****Privacy** → **Ads**
Depending on your system, you will either be given the option to delete your advertising ID or to "Opt out of interest-based ads". You should delete the advertising ID if you are given the option to, and if you are not, we recommend that you opt out of interested-based ads and then reset your advertising ID.
You will either be given the option to delete your advertising ID or to *Opt out of interest-based ads*, this varies between OEM distributions of Android. If presented with the option to delete the advertising ID that is preferred. If not, then make sure to opt out and reset your advertising ID.
### SafetyNet and Play Integrity API