Burner Phone 101

When I was working at EFF, I started writing (but never finished) a couple of essays along the lines of "the degree of trackability of mobile phones is an unfortunate accident, and we should fix it".

It basically comes from routing requirements (especially to receive incoming phone calls) combined with billing requirements (to make people pay for their connectivity) combined with the empirical requirement to see which base station a device is connected to, and which other base stations can see it at a given moment.

If you aggregate all of that data, then you know a (geographically moderate-resolution) complete history of where almost all people have been at almost all times, and patterns of their habits and whom they probably recurrently spent time with.

Not all of this data has to be collectable, because these things could be disaggregated by introducing different protocol layers. For example, you could pay the mobile company for data connectivity, but use cryptographic blinding mechanisms so that it doesn't know which specific subscriber obtained connectivity at a particular place and time. (Those blinding mechanisms could be implemented inside of SIM cards, so the SIM card's task is to cryptographically prove "I am a SIM card of a current paying subscriber of carrier X" rather than "I am SIM card number 42d1b5c0".) You could have device hardware IDs be ephemeral rather than permanent. Actual messaging and call services could all be "over the top" (as phone industry jargon puts it), provided by people who are not the phone company itself.

This disaggregation is a straightforward improvement from a privacy point of view because it prevents companies from knowing things about you that they didn't need to know in order to provide services.

Meanwhile, in the world we live in, we see governments trying to make it harder to make phones less trackable, by putting legal restrictions on changing hardware addresses, or requiring legal ID in order to establish service. I imagine that an additional cryptographic indirection layer in SIMs to prevent carriers from linking a permanent identifier to a network registration (or specific data use) would also be banned in some places if it were invented.

This shouldn't be inevitable. One thing that made me think about this was when there was a little scandal (which I was a small part of) about companies tracking device wifi MAC addresses for commercial purposes. There was a little industry that would try to recognize people and build commercial profiles based on recognizing that the same device was present (in fact, at the time, even if it didn't actually connect to the wifi -- because a typical wifi-enabled mobile device was sending broadcast wifi probe packets that included its MAC address). So Apple was like "this is a bad use of MAC addresses, which only exist to distinguish devices that happen to be on the LAN at the same time, and perhaps to allow network administrators to assign permanent IP addresses to specific devices", and they made iPhones randomize wifi MAC addresses for some purposes, mostly fixing that particular issue.

We could think just the same way about GSM networks: "these identifiers exist for specific protocol reasons; using them for device or user tracking is an abuse that should be mitigated technically".

If you need to communicate with people in your area and not be tracked; MeshCore software with LoRa hardware like the this https://lilygo.cc/en-ca/products/t-lora-pager is something to consider. Text only, completely offline

One thing I didn't see covered is to never have your "real phone" and your "burner phone" on you (or in the same location) at the same time while powered.

Easy enough to say "Gee...these 2 phones are always together or nearby when activated" or "this phone shuts off right before this one powers up".

Although, I suspect there are a few other ways to determine identity easier. Such as tracking the device identifier and then looking up nearby public facing cameras.

In many countries you need a valid government ID document to activate a mobile service which means burners do not really exist in those places.

Unless you bought a pixel, graphene’d it and then paid a homeless person to activate a pre-paid data only sim which you would top up with vouchers paid in cash and used a von and international voip service…

A lot of effort though

> Buy phone & service in cash

Step one is already difficult here in Australia: to do so you must hand over your personal details and ID. At least that was true for anything with a SIM card for sale back in the 2010s

So the “step 0” was “find a retailer who didn’t follow the rules”, and they’d usually be a corner store selling handsets or SIM cards by the bucket load to all sorts of interesting characters

eSim erodes privacy? Well, that sucks, because how long until Apple, Samsung, and Google decide the Sim slot should go the way of the 3.5mm headphone jack?

Kudos to this article for:

1. starting with threat modeling (though they don't call it that);

2. mentioning that your OPSEC affects not only you but also people connected to you; and

3. mentioning that maybe you should just leave the device at home (because it's basically a surveillance machine that you pay for).

(A more common article format would be to unload a pile of supposed security&privacy measures without putting them into context, and wouldn't properly set expectations for what that gives you. Neither of which is very helpful, and can be very counterproductive.)

I have the feeling that whenever you are on an airport (and maybe railway stations too) they cross your IMEI with the boarding pass info. I believe that in the UK police use some middle-man towers, which name I have forgotten, to collect as much data as possible.

While I like the sentiment of the article, I think most people are not aware of how hostile baseband firmwares are implemented on most SoCs that phones come with. Usually the cell tower handshakes that make you trackable can't be put off, meaning the modem will run in sleep mode even when you are in airplane mode (which is kinda funny considering the dangers of air travel, right? Right?).

Are there actually smartphones without an IMEI and with a Wi-Fi card only, preferrably not a Broadcom one?

> Radios off (GPS/Wi-Fi/Bluetooth) unless needed

GPS is a passive technology, no?

Downloading GPS assist data obviously isn't, and plenty of phones use wifi scanning as a way to augment GPS position fixes, but this seemed a strange callout. Am I missing something?

The Dumphone Finder (https://josebriones.org/dumbphone-finder) referenced there is useful, too, if you need to get a phone a 90 year old person has a chance of being able to use.

> Strong PIN, not biometrics

And also be aware of "shoulder surfing", which is different today in 2 ways it wasn't in the past.

In the past, the risk was something like someone looking at you type in your PIN on a bank ATM, or maybe your password on an computer keyboard.

Today, shoulder surfing is mainly different in 2 ways: (1) near-ubiquitous high-resolution surveillance camera networks, which can be places/scale and capture images that humans practically didn't; and (2) with machine learning, they don't even need to see what buttons you press, only see movements of your arm.

(Randomizing button positions on a touchscreen can help, and also help fight forensics like traces your fingers leave for where they touch. But randomization means you need to be able to see your screen, which reduces the ways you have to hide your screen from the view of others.)