Is it possible to 'un-format' xM1+?

#1

I have my xM1+ formatted for NDEF so it’s readable with most cellphones, but I am wondering if it’s possible to undo that process?

I originally formatted it for NDEF with either NFC Tools Pro or NXP TagWriter (I forget which, I use both) and it does work fine, readable by various NFC apps and even readable on the iPhone.

But now I’m considering a different usage that would work better if it wasn’t NDEF formatted, so I am trying to undo that process so it’s just a blank Mifare tag again.

I’ve tried with a few Android apps that have options to ‘Factory Format’ but they don’t seem to work. Or maybe they’re just re-formatting as NDEF again rather than going back to being a blank Mifare format…

Thanks!

#2

So you have a few options, your best being a proxmark3 and using the included lua script “remagic.lua” it sets magic gen1 chips back to factory programming.

The other option is to use the proxmark cli commands for gen1 chips to reset it, can’t recall how of the top of my head but will check when I can.

#3

Thanks @TomHarkness!

I haven’t played with the proxmark scripting stuff yet but I’ll check it out.

Edited to add:
There’s a script in there, “formatMifare.lua” which does exactly what I want, except it doesn’t work lol.

However – it prints out the actual proxmark commands and if I enter all the commands manually, one at a time, it does work! :smile:

Testing all this on a spare Mifare tag of course, not an implant of course lol.

Edited again to add:
Figured out why the script didn’t work lol. The line that did the actual command was commented out so it was just displaying but not doing. :smile:

#4

Sweet! So that script will format a blank mifare card. Not your xM1+.

Remagic.lua has the correct Hf14a raw apdu commands to set the gen1 chip back to the original state.

Edit: testing on a blank mifare card is not really compatible to a gen1 uid changeable chip. If you don’t have any you can buy some from hacker-warehouse or rfxsecure.

2nd edit - unless DT sell them, In which case by from them!! :slight_smile:

#5

Thanks Tom. The remagic script looks like it’s meant to ‘reset’ block 1 of the Gen1 chip? It doesn’t seem to do anything to the rest of the memory? I haven’t tried it on my xM1+ but just looking at the script it seems to just write block 1 to a sort of ‘default’ state.

What I wanted was to remove the NDEF formatting from the rest of the memory. Eg. remove the NDEF directory info from blocks 2 and 3, set keys A and B from all 16 sectors back to the factory default, set the contents of sectors 2-16 to 00, which is what the formatMifare script does.

I will see about getting some Gen1 cards to experiment with just in case tho, but I’m 99% sure that the formatMifare script does what I want. I don’t think the remagic script would break anything, but it doesn’t look like it’d actually remove the NDEF formatting.

Cheers!

Edited to add: I realized my PM3Easy came with a Gen1a card, so I just tested with that. Used the Proxmark to set the UID, then used the NFC Tools Pro app to format to NDEF and write a couple records to it. Verified with iPhone that it was readable, like my xM1+ is. Then I used the formatMifare script on proxmark, and it wiped everything to ‘factory’ again, so the card is no longer NDEF formatted.

Success, this is exactly what I wanted to do with my xM1+ if I do switch to the other use case. :smile:

#6

Amazing! I definitely misunderstood but glad you managed to test it on a card. Well done :slight_smile:

Just be careful with the coupling with your implant. Really don’t want to have any write issues with those commands - if something goes wrong you can potentially brick the xm1+.

#7

@RealVioletWitch how did you format it for NDEF to begin with? my tag was implanted yesterday and for a while it worked and then I accidentally used the erase tag feature within NFC tools getting it mixed up with format memory and now im unable to put any data on it at all??

#8

@Jpr98 I used an Android app, NFC Tools Pro. Just use the normal Write Tag option, and for MiFare tags it will automatically format the tag for NDEF when it writes the records.

#9

it seems to be coming up with “write error!”, the tag is reading correctly although at taking a closer look its coming up with “Tag type: ISO 14443-3A NXP MIFARE Classic 1k - Not Supported” from memory last night it didnt come up with that. Do you have any ideas or have you ever had this happen before?

#10

From what I remember, this may be a hardware issue with your phone?

The MiFare Classic requires a different ‘license’ or something. If the phone’s NFC chip is made by NXP then it works cos NXP made the tag and the chip and there’s no license issue. If the phone’s NFC chip is a 3rd party tho, then they can’t access the MiFare Classic tags because they aren’t licensed. I think.

This doesn’t apply to the xNT type of tags because those are under a different license arrangement or something, part of the NFC consortium standard or something like that.

You can check this in NFC Tools, if you tap the … thing and then About, scroll down and look for “check which NFC chips are compatible with your device” and tap that.

It compares your phone’s make/model against a database and will tell you what it is compatible with and what it isn’t.

This is from memory mind you, I could be wrong. But you should check the compatibility anyways just in case.

#11

not sure why but after just hitting try again over and over it is working again, possibly either a bad connection or just my phone playing up

#12

Ah good! Yeah sometimes the coupling can be touchy, like 1mm off and you don’t get a good write. Glad it’s working now! :smile:

#13

so it appears that the app was lying to me!! I tried to format as NDEF in TagWriter and it comes up with “this tag can’t be formatted” when I read the tag (in TagWriter) its giving me this:
Tag type and NFC storage size
Format the card before use

Content
No NDEF detected

not sure why half of this bolded either??

#14

We haven’t had much luck with TagWriter. NFC Tools Pro is the one that’s worked best for us, both with our xNTs and our xM1+s.

#15

i’ll give NFC Tools Pro a go and see what happens

#16

NFC Tools Pro is still giving me the same issues it formatted the memory fine but is still unable to write, its weird how overnight its gone from being able to be written on to now not working at all