Helldown is an emerging ransomware group first identified in August 2024, known for its fast-evolving and cross-platform threat capabilities. It exploits critical vulnerabilities—most notably CVE-2024-42057 in Zyxel firewalls—for initial access and demonstrates modular design and anti-detection mechanisms. Helldown targets both Windows and Linux environments, including VMware and ESXi systems. It employs a double-extortion strategy: encrypting files with randomized extensions via executables like hellenc.exe, and threatening victims with data dump releases via its Tor-hosted leak site.