Hidden Data in NFC Tags


Various NFC icons.

I've just got a set of wearable NFC tags, and I've discovered something interesting about the way data is stored on them. tl;dr Overwriting a tag can leave old data intact, and still readable. Here's the decoded memory layout of a tag with data written to it. In this case, a (failed) experiment at storing a JavaScript pop-up. # NDEF message: [00] D1 01 7D 55 00 64 61 74 61 3A 74 65 78 74 2F 68 …

Continue reading →