How attackers use Brute Ratel (BRC4) by Lucie Cardiet

This report describes Brute Ratel C4 (BRC4), a sophisticated post-exploitation command-and-control framework abused by real-world attackers, detailing its stealth and evasion features (userland unhooking, sleep masking, indirect syscalls), flexible payload and listener configurations, credential theft and lateral movement techniques, fileless/process injection capabilities, and Vectra AI’s detection approaches mapped to the MITRE ATT&CK framework.