Mythic

GOFFEE Dissects Custom COW Agent Forked from Poseidon Mythic Implant

Angara Security researchers uncovered a custom Go-based Mythic C2 agent named COW used by the Russian-oriented APT group GOFFEE, also known as Paper Werewolf. The agent represents an independent development branch derived from the public Poseidon project rather than its Freyja fork. Samples were heavily protected with Garble obfuscation and a modified UPX packer that required manual header reconstruction for unpacking. Analysis of surviving strings, build paths, and architectural features confirmed Poseidon origins while revealing numerous custom modifications including Windows support, additional C2 profiles, and new command implementations. The group employs the agent alongside other tools such as PowerTaskel, MiRat, and BindSycler for persistent access to Linux and Windows systems across government, energy, telecom, and defense targets. Researchers traced multiple variants through VirusTotal and incident reports, documenting evolutionary changes in configuration handling and peer-to-peer communication mechanisms.