Overview
An image is provided with colored 2x3 grid grids representing characters.
Reconnaissance
The colored grids are characteristic of the Hexahue cipher, which represents the alphabet using combinations of primary/secondary colors.
Exploitation Strategy
Translating the grids to ASCII letters spells out the string AVANANEE.
Solution Code
Map each 2x3 color grid to the Hexahue alphabet key -> AVANANEEFlag
STG{AVANANEE}