Wednesday, July 25, 2018

Wristband Teardown from Amazon's #FireTVSDCC Event at San Diego Comic Con

A friend returned from San Diego Comic Con 2018 with an RFID bracelet used to track users in the Amazon Fire TV experience (on Twitter, #FireTVSDCC).  This is a teardown of the bracelet after the event.  At this time, I was unable to read from the bracelet.



The bracelet is fairly simple with a cloth band and plastic/paper tab threaded through.  The closure is plastic and one-way.  It bites into and mangles the cloth band if you attempt to remove, but you could probably shim it with tools and practice.  Might be a fun thing for the Tamper Evident Village if it turned out events were trying to use this for access control like plastic self-destructing wristbands.


The back contains a serial number.  I would like to see if this serial number would match the data read off the tag.



Separating the badge by prying them apart, I  spot the prize: an adhesive RFID tag placed between the glossy plastic covers.  It appears to have a model number of "CXJ-040" in the center of the tag.  It uses a circular antenna.  CXJ is the initials of Shenzen manufacturer ChuangxinjiaTheir product pages show many similar wristbands in a few different frequencies.

The tag didn't respond to my Android phone, so it is not a Mifare or similar.  Hopefully I can find a reader at the local Hackerspace or DEF CON 26.

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