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Tunnelling

Browser data over DNS

Browsertunnel sends arbitrary browser data through DNS prefetch requests. The channel is one-way because browser JavaScript cannot read the DNS answers.

browserDNSdata transfer

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Screenshot used in the talk for Browser data over DNS
Screenshot used in the original talk.

The browsertunnel proof of concept sends arbitrary data from a browser in DNS prefetch requests. Communication is one-way: browser JavaScript cannot read the DNS answers, so the technique cannot return data to the page.

The example shows how browser features can create an outbound data channel through DNS, with the one-way limit shaping what it can do.

Primary source: https://github.com/veggiedefender/browsertunnel