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#1 2020-05-18 20:51:35
- thetruth
- Contributor
- Registered: 2020-05-17
- Posts: 4
LF question - How did I corrupt my card?
Hi all,
I've done a bit of work with hf keys with good amounts of success, but recently I decided to work with a lf card for the first time.
After doing a few commands just to test it out, the card was unresponsive (both to Proxmark and to the actual readers). My question is: What command caused this?
I will try to walk through exactly what I did, unfortunately I didn't log my output (and now that the card is unresponsive, I can't replicate it).
Commands I used:
lf search - Came back that it was a t55xx card (at this point I probably should have used detect to verify, but didn't)
lf t55xx config
lf t55xx info
lf t55xx read
lf t55xx bruteforce [r 2] aaaaaaaa bbbbbbbb (example from proxmark)
My guess is the bruteforce can corrupt the card somehow, but I wanted to ask here to make sure that the other commands only read data, and do not write anything.
Also, here is the data plot of the card right now. What does this signify? I'm really not sure what's going on here...
https://imgur.com/a/Vtjj6d4
My goal is to learn from this and not corrupt other cards, so please let me know any information you can give me 
Thanks!
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#2 2020-05-18 23:07:43
- thetruth
- Contributor
- Registered: 2020-05-17
- Posts: 4
Re: LF question - How did I corrupt my card?
Alright so I figured out the bruteforce command was the culprit (as I'm sure most of you knew). I realize now that if an lf card is not configured with the password bit set, using commands like this can brick it.
Luckily, I've been able to restore it with wipe. However, I still am curious about the data plot. Why was I getting this wave? Just curious.
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#3 2020-05-19 08:36:10
- mwalker
- Moderator
- Registered: 2019-05-11
- Posts: 318
Re: LF question - How did I corrupt my card?
Side comment, its the T55xx that can have the issue you found. Other LF cards may not have the same issue.
If you really want to know what happened, check out the data sheets for the T5577 if you look close enough, you will find that sending a read command with a password when a password is not needed can look like a write without a password. If you then map the command data, we will find out what you sent to the card and why it "stopped" responding.
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