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33C3 talk on dissecting cellular modems (gnumonks.org)
105 points by BuuQu9hu on Dec 31, 2016 | hide | past | favorite | 15 comments

Here's the recording:


(I prefer media.ccc.de over YouTube because it lets you download the video in at least a couple of formats, and sometimes offers alternate streams/languages.)

Related: The YouTube and stream dump problem


Wow, had been following a ccc account on YouTube for some years, had no idea it wasn't official. Now subbed to the real source - thanks. :)

Just to make sure there are no misunderstandings: the mediacccde account is official:

> To mitigate this we have decided to open an official media.ccc.de YouTube channel to at least make sure users don’t have to suffer advertisements, incorrect licenses and incomplete metadata. This account can be found on https://www.youtube.com/mediacccde.

I quite like the ability to watch videos on YouTube at 1.5x or 2x speed.

Note, one can do the same with ffmpeg:



Most video players support changing the playback speed. In mplayer it's controlled with the '[' and ']' keys and in VLC it's set in the Playback -> Speed menu.

HTML5 video elements also usually have a playback speed property that can be changed in the JS console, so any site that streams fast enough can be sped up.

The mplayer keys work in VLC too, BTW.

So can I really write AT+QLINUXCMD to my USB LTE Modem over tty-over-USB and execute arbitrary shell commands on the modem's internal linux installation as root?

It's still present even in the latest EC20E firmware EC20EQAR02A09E2G from 2016-09-24:

  ynezz@ntbk:/opt/devel/flexisbc/quectel_ec20/EC20EQAR02A09E2G$ grep QLINUXCMD
  Binary file 9615-cdp-recovery-image-9615-cdp.yaffs2 matches
  Binary file dsp2.mbn matches
  Binary file 9615-cdp-usr-image.usrfs.yaffs2 matches
Edit: formating

Would Sierra Wireless 313U be a good candidate?

If your USB LTE Modem is a Quectel (or maybe Sierra Wireless) MDM9615 based modem, yes. Otherwise, no.

If I remember the talk correctly, then yes. But it was said that there are several distinct firmwares…

system() is one of the most abused function in that code.

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