Sector 0 contains the manufacturer information and often the tag ID. This is a MiFare Classic 1k, which holds 1,024 bytes of data, made up of 16 sectors each split into 4 blocks of 16 bytes. Reading the Tagįirst a brief introduction to the MiFare Classic data structure. Note that I have skipped over the already well-documented process of reading the MiFare Classic tag, but details can be found at in the links at the bottom of this post. This article will present a walk-through of my process for investigating an unknown implementation of contactless technology. There was an inherent trust that the bands were secure from tampering, but a little investigation with a mobile phone reveals the first flaw - the bands used the vulnerable MiFare Classic technology and could be easily broken.

You could go and spend it at various stalls, and any remaining cash on the wristband would be returned to you when you left the event. You handed over your cash to a staff member armed with a device that looked like a heavy-duty mobile phone, and they added that same amount of virtual cash to your wristband. Recently I attended an event that used wristbands as a form of cashless payment for food and beverages. The approach I have taken is to look at practical attacks - how implementation (often combined with insecurities or misuse of technology) can lead to real issues. I have spoken at many events on contactless card security, and the different methods by which our most common 'secure' card systems can be cloned, modified, or disrupted.

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