Fog Ransomware Attack Chain Leverages Legitimate and Open-Source Tools

Researchers observed a Fog ransomware attack against a financial institution in Asia in which operators blended uncommon legitimate and open-source tools (notably Syteca, GC2, and Stowaway) alongside common utilities (PsExec, Impacket, 7-Zip, MegaSync) to steal credentials, move laterally, maintain persistence, stage exfiltration, and deploy ransomware; Fog is a STOP/DJVU variant that disables defenses, deletes backups, uses AES-256 with RSA-2048 for keys, and has adopted double-extortion tactics.