Profiling Jodel™ users with image (meta)data

how jodel works Users can can start discussion threads by posting a so called "jodel" which consists of a text message or an image. Others within a 10km radius can comment on it as well with text or image content.



Within every thread a commenting user gets assigned a ascending number (starting from 0 - OP gets 0 by default) that won't change for all his comments and is publicly visible. This way you can mention someone specific and don't loose track of who says what. Quite practical because comments are in a flat hierarchy and not threaded.



In a single thread users are thereby pseudonymous though across the overall app they are anonymous to everyone else.



Users of the app like this advantage of anonymity to express themselves in a much more open way and share personal, intimate and often embarrassing content.

not

off-topic This can be done by intercepting the network traffic to see the payloads the app and the jodel server exchange. Like many services jodel uses and http api that feeds the app with information to display.



Taking that approach you will have to ssl unpin the app first.



Another way would be to act like an fake client and get the payloads this way.

% domain="http://img.jodel.com/" % file="5b9466bfec02b67c7e09889e_ChrvVB8OpM9c1Ubr_image.jpeg" % curl -O "$domain$file"

% exiv2 5b9466bfec02b67c7e09889e_ChrvVB8OpM9c1Ubr_image.jpeg File name : 5b9466bfec02b67c7e09889e_ChrvVB8OpM9c1Ubr_image.jpeg File size : 107092 Bytes MIME type : image/jpeg Image size : 640 x 1100 Camera make : Camera model : Image timestamp : Image number : Exposure time : Aperture : Exposure bias : Flash : Flash bias : Focal length : Subject distance: ISO speed : Exposure mode : Metering mode : Macro mode : Image quality : Exif Resolution : 1080 x 1857 White balance : Thumbnail : None Copyright : Exif comment :

% identify -format "%[EXIF:*]" $file exif:DateTime=2018:09:09 02:17:55 exif:ExifOffset=94 exif:ImageLength=1857 exif:ImageWidth=1080 exif:LightSource=0 exif:Orientation=0

% exif $file EXIF tags in '5b9466bfec02b67c7e09889e_ChrvVB8OpM9c1Ubr_image.jpeg' ('Motorola' byte order): --------------------+------------------------------- Tag |Value --------------------+------------------------------- Image Width |1080 Image Length |1857 Orientation |Unknown value 0 Date and Time |2018:09:09 02:17:55 X-Resolution |72 Y-Resolution |72 Resolution Unit |Inch Corrupt data The data provided does not follow the specification. ExifEntry: The tag 'LightSource' contains data of an invalid format ('Long', expected 'Short'). Light Source |%