Mirage Kitten

Iran-Linked Tortoiseshell Group Deploys Malicious wtsapi32.dll Backdoor for Persistent Windows Access

Researchers have uncovered new tools deployed by the Tortoiseshell group, an Iranian-linked threat actor also tracked as Mirage Kitten, UNC1549, and Nimbus Manticore. The campaign features a Windows backdoor disguised as the legitimate wtsapi32.dll library that silently establishes reverse SSH tunnels over port 443 to maintain access to compromised networks. Active since at least 2018, the group has targeted defense, aerospace, technology, IT services, and military organizations primarily in the Middle East and the United States. The malware preserves expected Windows API functions while enabling command execution, file exfiltration, in-memory DLL loading, directory listing, and system reconnaissance. Associated infrastructure spans the United Arab Emirates, Saudi Arabia, the United Kingdom, Belgium, Canada, Australia, and Japan.