<story><title>Reverse engineering a mysterious UDP stream in my hotel (2016)</title><url>https://www.gkbrk.com/2016/05/hotel-music/</url></story><parent_chain><item><author>unwind</author><text>Today (but perhaps slightly less in 2016, not sure) you could easily imagine a microcontroller (or FPGA) with a microphone that bugs you, but encodes that audio (using steganography) onto a canned audio file of elevator music, and then sends the result over the network &amp;quot;in the open&amp;quot;.&lt;p&gt;To a casual observer snooping the relevant network, it would probably (as here) look as elevator music, but to the intended recipient who can decode the steganography, it would be a covert listening device.</text></item><item><author>blueberrychpstx</author><text>okay this is way over my head - but this would have to be steganography hiding in the audio file that could only be run by someone like OP, detecting; downloading; etc the udp data, right?</text></item><item><author>kibwen</author><text>&lt;i&gt;&amp;gt; But what was this audio? Was this a sneakily placed bug that listened to me? [...] I can’t believe I spent time for this. It’s just elevator music.&lt;/i&gt;&lt;p&gt;Joke&amp;#x27;s on you, it&amp;#x27;s a bug listening to you in your room while using steganography to merely appear to be elevator music!</text></item></parent_chain><comment><author>koolba</author><text>Even better than a canned audio file would be machine generated music. Otherwise you could detect that the “same” song is being transmitted with slightly different bits.&lt;p&gt;Or you could have an extremely long audio file so the repeat situation doesn’t occur.</text></comment>
<story><title>Reverse engineering a mysterious UDP stream in my hotel (2016)</title><url>https://www.gkbrk.com/2016/05/hotel-music/</url></story><parent_chain><item><author>unwind</author><text>Today (but perhaps slightly less in 2016, not sure) you could easily imagine a microcontroller (or FPGA) with a microphone that bugs you, but encodes that audio (using steganography) onto a canned audio file of elevator music, and then sends the result over the network &amp;quot;in the open&amp;quot;.&lt;p&gt;To a casual observer snooping the relevant network, it would probably (as here) look as elevator music, but to the intended recipient who can decode the steganography, it would be a covert listening device.</text></item><item><author>blueberrychpstx</author><text>okay this is way over my head - but this would have to be steganography hiding in the audio file that could only be run by someone like OP, detecting; downloading; etc the udp data, right?</text></item><item><author>kibwen</author><text>&lt;i&gt;&amp;gt; But what was this audio? Was this a sneakily placed bug that listened to me? [...] I can’t believe I spent time for this. It’s just elevator music.&lt;/i&gt;&lt;p&gt;Joke&amp;#x27;s on you, it&amp;#x27;s a bug listening to you in your room while using steganography to merely appear to be elevator music!</text></item></parent_chain><comment><author>sublinear</author><text>&amp;gt; to the intended recipient who can decode the steganography&lt;p&gt;Not just decode, but also decrypt.&lt;p&gt;You&amp;#x27;d probably want to encrypt not just for the secrecy, but so that the noise introduced by the steganography doesn&amp;#x27;t seem so suspicious.</text></comment>