Government Wireless Emergency Alert

curious_liberal

Hi there, I'm from the UK. Today it was announced that on the 23rd of April the government will be testing the emergency broadcast system and that our phones will be unable to perform other actions other than making an alarming sound until we acknowledge the message.

I went to disable this in settings but was met with a message underneath the toggle to disable WEA (wireless emergency alerts) claiming that, "National warning messages issued by the President. Can't be turned off". After speaking to some other people we've discovered that this is most likely left over from the AOSP on certain languages such as English UK; those using a US language pack do not see this message. Unfortunately I am unable to verify whether this is true or not. Consequently I decided to uninstall "com.android.cellbroadcastreceiver.module" using ADB due to the confusion. I am now told that this has made my device insecure because I've made changes using ADB. I am unsure how to reinstall this package and revert my changes to secure my device. Any help and information regarding the matter would be much appreciated. Thank you.

[deleted]

curious_liberal don't do anything, wait for next system update or you can factory reset but I think that is not worth it. As matchboxbananasynergy said you can opt out in Settings - Safety and emergency - Safety and Emergency Alerts or just switch to network lower than 4G for that day.

Bobby123

I've just noticed it is on my GrapheneOS phone. I was expecting this to not be present?
Can I ask why it is there and if you are allowing the government to restrict mobile features if you don't acknowledge the alerts?

Bobby123

I would have thought the whole point of GOS is to take back control and prevent these kind of things?

matchboxbananasynergy

Bobby123 See here:

https://discuss.grapheneos.org/d/3989-uk-gov-alert-on-grapheneos/2

Bobby123

matchboxbananasynergy

Thanks

[deleted]

Unless you have opted out of presidential alerts, this should take place at 3pm today (UK)

RichQuartz

Interestingly didn't recieve the alert on my Pixel 6 Pro here, however did have Presidential Alerts enabled...

pdagenius

I deliberately turn off emergency alerts to see what would happen. No alert and nothing in the alert history. Have a 6a.

[deleted]

It was a network broadcast over 4G or 5G. I did receive mine.

Ian831

Same here

seriously-compromised

I confess I am more than a little concerned at the "official" attitude regarding the presence of this clear vulnerability.
I won't speculate what the reasons are for not closing this gaping hole but, I suspect that using this os does little more than identify me as a person of interest, worthy of closer scrutiny!

This is my first post here as a new user and I feel like somebody yanked the carpet out from under me...

other8026

seriously-compromised clear vulnerability

It's not a vulnerability, it's a system app/service that receives emergency messages.

Also, it's all open source. Take a look at it here: https://github.com/GrapheneOS/platform_packages_apps_CellBroadcastReceiver/. You're far from the first person to mention wireless emergency alerts this way, so I have actually looked through a lot of the code for WEA, and what I saw was all very boring.

I noted some of the reasons for the permissions, which I'll share here so that (hopefully) people stop freaking out so much about it:

SMS - Some alerts can be saved to the messages store. SMS permissions allow it to do that.
Interact across users and manage users - The only thing I could find was a check to see which user is active to avoid saving the message multiple times (since the SMS message store is global). It checks if the logged in user is the admin user to restrict changing settings if not. It also checks if the user is logged in.
Bluetooth - Checks if phone is connected to audio device. Checks if phone is connected to a "companion" device, and sends to companion device if necessary.
Keyguard - Display over the keyguard when the device is locked.
Read (privileged) phone state - Check if the user is in a call, get carrier config, get carrier ID (to reset settings if/when a new one is used).

All of this is very boring and its permissions all make sense when you actually look at it rationally.

seriously-compromised I suspect that using this os does little more than identify me as a person of interest, worthy of closer scrutiny!

Unlikely, but regardless it's not going to be wireless emergency alerts that's going to tip them off that you are using GrapheneOS. There's nothing wrong with using an OS and unclear why using an OS that's known for improving mobile privacy and security would make you a person of interest.

seriously-compromised

Thanks for replying. However I remain unpersuaded... I have learnt over my many years on this ball, If any sort of opening presents itself, somebody will eventually drive a bus through it and swipe all your twinkies. And I should be specific: it's WEA I am uneasy about, not Graphene. I sincerely apologize for casting aspersions. In my hysteria I temporarily lost the use of my prefrontal cortex.

I will state for the record I am extremely grateful for the manifest years spent building Graphene OS. Very grateful indeed. I find this os intriguing and shall continue to explore it but... my organic alert mechanism has been tripped. It has never once gone off for specious reasons, like WEA has so many times. I live in wildfire territory and like many others in these here parts I am very familiar with how that system has been abused. I am trying in vain to find the local news story that went into some depth about how the app was used to identify and track folks that refused to just walk away from their whole world, after the authorities deemed their livestock and possessions unworthy of saving but, I digress...

matchboxbananasynergy

seriously-compromised If you're not using airplane mode, your location can be determined through triangulation. WEA does nothing to amplify or make that worse.

If you're using airplane mode, WEA also ceases to function.

If you don't want to receive these alerts, you can turn them off, with the added bonus of being able to also disable "presidential alerts" which cannot be done in AOSP. The reason we allow disabling those is to offer people more choice, and also because it is abused in countries like Canada, where every alert is sent as a presidential alert, removing the choice from people to choose what types of alerts they want to receive.

You seem pretty firmly set on thinking that wireless emergency alerts are a threat. @other8026 has already done a pretty good job explaining how and why that's not the case. If you "remain unpersuaded" by that, I don't think there's much else that I could explain that would persuade you. The code is right there.

zzz

seriously-compromised

I am very familiar with how that system has been abused. [...] the app was used to identify and track folks

Sounds like you're worried about giving up your location data to authorities.

Like others have said, this is likely fundamentally an issue with the SIM card provided by your carrier (Verizon, AT&T, etc) and the laws that govern those orgs.

Fundamentally its not an "app" that's doing the tracking.
Its your relationship to your cell coverage carrier, which is mediated by your SIM card.

These WEAs are just one very small, visible slice of the constant cell tower activity that locates you and your device, at all times (as long as airplane mode is off and the SIM card is enabled).

If you're worried about abuses and retaliation enabled by your cell carrier's location tracking in that wildfire scenario, like others have said you could consider putting your SIM-carded devices in airplane mode during these emergencies.
You could stay informed during such times via old-school AM/FM radio, maybe?

I recently shared some links with more detail about how cellular location tracking can be used and abused by 3rd party orgs:
https://discuss.grapheneos.org/d/13838-people-who-use-sandboxed-google-stuffsocial-apps-why/46

If any sort of opening presents itself, somebody will eventually drive a bus through it and swipe all your twinkies.

You're right to be protective of such openings!
Fortunately, GOS gives you the choice to close it up as long as you want, so long as you can stomach living life during that time without the internet in your pocket.

other8026

zzz These WEAs are just one very small, visible slice of the constant cell tower activity that locates you and your device, at all times (as long as airplane mode is off and the SIM card is enabled).

I'm not aware of this activity being "constant." I was under the impression that providers just push a special kind of message out to all connected (or subscribed?) devices when an alert is pushed out. I could be wrong about this, of course, but I'd like to know where you learned that it's "constant."

zzz

other8026

I should have been clearer - I meant that the sum total of all SIM card activity on a phone is constant (pinging to negotiate a connection to cell towers, like to know if there are any new SMSes, mobile data packets, voice calls, etc ready for a particular phone), and WEAs can be just a small intermittent portion of that activity.

In that citizenlab report I posted in another thread, they cite an example from Saudi Arabian surveillance operators who purchased location data as part of an active attack on targeted people in the USA. In section 3 they write:

Data in Table 2 calculates the total number of tracking messages which were received from Saudi Arabia network operators during a 24-hour period, broken into hourly segments. Based on these single day statistics, each mobile phone was geolocated approximately every 11 minutes.

https://citizenlab.ca/2023/10/finding-you-teleco-vulnerabilities-for-location-disclosure/#roaming-sims-and-services-101

The EFF also did an interesting report about how Stingrays work, where they mention this in passing:

A fundamental aspect of wireless technology is the paging model. When the network has a message it wants to route to a phone, it sends an “RRC paging message” which is received by every phone listening to their carrier’s paging frequency in that area (which is basically every phone), asking for that particular phone to contact the base station to negotiate completing a connection to receive a call or message. Thus, phones are constantly listening for RRC paging messages and receiving and discarding ones not addressed to them.

Also:

Additionally, phones periodically transmit unencrypted messages about their location and measurements of cell service quality that anyone with the right equipment can easily intercept. Sometimes these messages contain the phone’s exact GPS location, but usually the information about the signal strength of nearby cells is enough to calculate the phone’s location.

https://www.eff.org/wp/gotta-catch-em-all-understanding-how-imsi-catchers-exploit-cell-networks

I wish I had a better source for how often these pings typically are in the case of location data-harvesting passive attacks (which would indicate how granular the location tracking could be for most folks in the general case - 1 ping/5ec is very different from 1 ping/day).
I've heard some numbers in the past but I don't want to spread hearsay - I'll keep looking for a good source.

AlanZ

I don't know to what extent people appreciate the capability to turn off ### all government alerts, but to me this was one of the features that cemented my wish to stick with GOS.