I was hoping for some sort of image or binary processing exploit too, but the attack just uses a Postgres vulnerability to execute arbitrary shell code. [0][1] The fact that the executed code was buried in an image seems to just be a camouflage step for the attacker.

0. https://github.com/nixawk/pentest-wiki/blob/master/2.Vulnera... 1. https://www.rapid7.com/db/modules/exploit/linux/postgres/pos...