Posts Tagged ‘hex’

Hackvent 2019: Day 5

05 Dec 2019
CTF: Hackvent 2019
Link to challenge:
Date Completed: 5 December 2019



HV19.05 Santa Parcel Tracking

Image mirror:


Initially we try scanning the barcode as it looks like a Code 128 barcode. It works but gives us the string Not a solution which is unfortunately a dead end. After a lot of experimentation, we manually note down the hexadecimal values for each colour in sequence. We decided to use Photoshop’s colour picker but in hindsight should have done this pragmatically using MATLAB.

This gives us the following list of 64 hex codes:

After more experimentation, we discover that the blue channel of each hex code is significant! We discard all data but the blue channel and run our sequence of hex codes through an online hex to ascii converter.

This gives us the following string which has our flag surrounded by what appears to be noise:

Flag:  HV19{D1fficult_to_g3t_a_SPT_R3ader}

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Posted in Hackvent 2019