Hello, welcome to the Friday, April 21st, 2017 edition of the Sansonet Storm Center's Stormcast.

My name is Johannes Ulrich, the time recording from Jacksonville, Florida.

Let's start today with a good reminder from Xavier to watch your DNS logs.

I always keep saying it's probably one of the most useful logs to watch if you have to pick one.

And in this case, again, it's about very large, very long DNS queries that are often used in indicative of covert channels.

Xavier uses a little bit of different trick than what I usually do. He uses the

base 32 command in order to encode the data. I usually just use XXD. The result is similar.

Base 32 is probably actually a little bit more efficient. And apparently the W3C, the organization that is behind many web standards, is considering

making ambient light sensors in devices accessible via JavaScript. Ambient light sensors are

typically used to dim or brighten displays in order to adjust them with the surrounding in some more modern,

fancy devices. They also adjust the color temperature to the temperature of the light in the room.

Now, with this JavaScript extension, JavaScript would have access to the sensor and with that,

of course, would learn more about the

environment the phone or the computer is used in which has some privacy implications.

Now this standard is far from finalized yet so not exactly clear what like for example the update

frequency is or the

granularity of the readout, but in a proof of concept, a demo, a researcher was able to, for

example, read QR codes and other data displayed on the screen, including, for example,

to identify popular websites. Now, based on the demo, it's my example, to identify popular websites.

Now, based on the demo, it's my impression this was sort of a best case, so likely the

details won't be as granular as in this demo, but overall, of course, it could certainly

leak information about the user. Personally, I could see some form of covert channel where you have some device in the room that changes lighting conditions,

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