/usr/share/afterstep/backgrounds/Plain_Textures/ is in afterstep-data 2.2.12-6.
This file is owned by root:root, with mode 0o755.
..
/usr/share/afterstep/backgrounds/Plain_Textures/.include
/usr/share/afterstep/backgrounds/Plain_Textures/Blurts_Michelson
/usr/share/afterstep/backgrounds/Plain_Textures/Blurts_Michelson.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Checkers
/usr/share/afterstep/backgrounds/Plain_Textures/Checkers.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Defenseless_Elsie
/usr/share/afterstep/backgrounds/Plain_Textures/Defenseless_Elsie.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Dorchester_Consolidated
/usr/share/afterstep/backgrounds/Plain_Textures/Dorchester_Consolidated.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Drop_Injures
/usr/share/afterstep/backgrounds/Plain_Textures/Drop_Injures.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Evil_Car_Wash
/usr/share/afterstep/backgrounds/Plain_Textures/Evil_Car_Wash.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Gray
/usr/share/afterstep/backgrounds/Plain_Textures/Gray.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Libelous_Paintings
/usr/share/afterstep/backgrounds/Plain_Textures/Libelous_Paintings.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Nordic_Powder_Pirate
/usr/share/afterstep/backgrounds/Plain_Textures/Nordic_Powder_Pirate.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Psychiatrists_Imminently
/usr/share/afterstep/backgrounds/Plain_Textures/Psychiatrists_Imminently.mini
/usr/share/afterstep/backgrounds/Plain_Textures/Simple
/usr/share/afterstep/backgrounds/Plain_Textures/Simple.mini