Beneath the Surface

Description: On the surface, this signal is nothing but meaningless noise — a mere whisper of the wind. But dive deeper into this transmission, and a storm begins to take shape, with gray skies gathering on the horizon. Can you navigate through the static and uncover what lurks beneath the surface of the wav — before it’s too late?

File

Solution

exiftool beneath_the_surface.wav
ExifTool Version Number         : 13.30
File Name                       : beneath_the_surface.wav
Directory                       : .
File Size                       : 6.3 MB
File Modification Date/Time     : 2025:07:13 12:40:18+02:00
File Access Date/Time           : 2025:07:13 12:40:19+02:00
File Inode Change Date/Time     : 2025:07:13 12:40:18+02:00
File Permissions                : -rw-r--r--
File Type                       : WAV
File Type Extension             : wav
MIME Type                       : audio/x-wav
Encoding                        : Microsoft PCM
Num Channels                    : 1
Sample Rate                     : 8000
Avg Bytes Per Sec               : 16000
Bits Per Sample                 : 16
Title                           : Generated audio
Software                        : fldigi-4.2.07 (libsndfile-1.0.28)
Comment                         : WEFAX576 freq=14011.900
Date Created                    : 2025:07:11T10:21:36z
Duration                        : 0:06:35

The Software and Comment fields are useful, these indicate that the audio file was generated by fldigi which contains a WEFAX (Weather Facsimile) image, transmitted at 576 lines at a frequenct of 14011.900 kHz. So, I install fldigi with yay -S fldigi (I use Arch, btw). Open the program and go to Op mode -> WEFAX -> WEFAX576, and then, on the main window, set the frequency to 14011.9 kHz. Now, upload the file on File -> Audio -> Reproduction. Please be patient and wait for the program to decode the entire audio and get the flag.

L3AK{R4diOF4X_1S_G00d_4_ImAG3_Tr4nsM1sSiON}

Author: tatore