There is not much you can do with just a card and a Proxmark3 or Flipper Zero. There is no card-only attack vectors. There are however reader/card vectors but that is outside the scope of this note.
Your iCLASS SR/iCLASS SE/SEOS credential has a SIO (Secure Identity Object) that stores your access control information also known as the PACS payload. We will need to extract the SIO with one of the methods outlined below and write that data onto a Picopass or a T5577.
In short:
We are downgrading from a secure credential to a lesser secure legacy format
# Success rate
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Unfortantely not all readers will have iCLASS legacy enabled and your **downgrade** will not work. The good thing is that **most** readers are left in their default configuration with iCLASS legacy enabled which allows us to easily take your secure credential and make a logical copy onto a less secure format. We can easily test if the reader is standard keyed and will accept a credential downgrade attack with the steps below.
# Getting started
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For the next steps, you will need a `Proxmark3` or `Flipper Zero` device.
## Verfiy reader has iCLASS legacy enabled
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Present a standard keyed iCLASS legacy credential at the reader and see if it beeps.
If the reader beeps, proceed to [Write a downgraded iCLASS legacy credential](#write-a-downgraded-iclass-legacy-credential)
Instructions:
To check if your legacy credential is standard keyed.
PM3
`hf iclass dump --ki 0` if it dumps == standard key
F0
`Picopass app > Read card` check if key == standard
## Inspect reader with HID reader manager
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Install [HID reader manager](https://play.google.com/store/apps/details?id=com.hidglobal.pacs.readermanager&hl=en&gl=US) and register before proceeding
A Android phone with NFC is recommended for this next step as iPhone can only inspect readers that are bluetooth enabled natively or have a BLE backpack installed as a add-on.
This method of inspection will not work if the reader has a MOB key or ELITE key.
Reader inspection is only possible on official HID readers, not third party readers using HID credentials.
Click use NFC and hold the phone to the reader and follow the prompts. Click on apply template.
<imgwidth="299"alt="Reader Manager Home Screen"src="./img/readermanager_1.png">
If you have successfully confirmed that iCLASS legacy is switched on then proceed to the next step
## Verify reader has ProxII enabled
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You can verify that the low frequency ProxII is enabled by using one of the following methods:
* Hold a [RF field detector](https://sneaktechnology.com/product/rf-detector-by-proxgrind-2/) at the reader and see if the RED LED flashes
* Use the Flipper RFID detector app `apps > tools > RFID detector` and make sure RFID symbol is active
* Use [reader manager](#inspect-reader-with-hid-reader-manager) and inspect the reader and check if 125khz prox is enabled at the bottom of the credentials page
## Test files
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Below are two dump files provided for easy testing.
- run the follwing command to restore hf-iclass-dump.json to a picopass card
`hf iclass restore -f hf-iclass-dump.json --ki 0`
F0
- Drop the iclass-flipper.picopass file here and write to card on Flipper
`qflipper > SD card > apps data > picopass`
# Simulate a standard keyed iCLASS legacy credential
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For [Test files](#test-files) if needed.
Instructions:
Once you loaded the file and started the simulation. Hold the device to the reader. If it beeps, proceed to [Write a downgraded iCLASS legacy credential](#write-a-downgraded-iclass-legacy-credential)
PM3
```
hf iclass eload -f hf-iclass-dump.json
hf iclass sim -t 3
```
F0
`qflipper > SD card > apps data > picopass`
drop iclass-flipper.picopass file here and simulate on Flipper
Prequisite, you must already have a [NARD add-on board](https://github.com/killergeek/nard) and a HID SAM
If not, you can buy a [kit](https://www.redteamtools.com/nard-sam-expansion-board-for-flipper-zero-with-hid-seos-iclass-sam/) from RTA webshop.
Follow these steps:
1. Launch Seader application
if `credential == iClass` use read picopass
if `credential == SEOS` use read 14443A
2. Place flipper on credential and read
3. Save as picopass
4. Go to picopass app and write your credential to a card
## Using Weaponized HID Reader
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OBS!
This method involves more technical steps, wiring, and is recommended for advanced users. If this is your first time with RFID technology and downgrade attacks, we suggest any of the two options above.
Prequisite, you will need the following bill of materials (BOM):
* A standard keyed iCLASS SE reader
* A ESPKEY [Github project](https://github.com/rfidtool/ESP-RFID-Tool)
* Some 20-24 AWG wire or ethernet cable
* Your preferred power source (5-9v)
The easiest way is to buy a [ESPKEY](https://www.aliexpress.com/item/32850151497.html)
Follow these steps:
1. Connect the `Data 0, Data 1, Ground, Power` to the respective terminals on the ESPKEY
2. Provide 5-9V power to the reader and ESPKEY at the same time using your preferred power source
IT IS ABSOLUTELY NECESSARY THAT THE READER AND ESPKEY SHARE THE SAME GROUND EVEN IF YOU ARE POWERING ESPKEY AND READER SEPERATELY
3. Connect to the wifi network the ESPKEY and navigate to `192.168.1.1` for the interface
4. Scan your credential on the reader
5. Open `log.txt` and copy the binary string WITHOUT the preamble
