🔴 Antino Backdoor Lets China-Linked UAT-11587 Turn Microsoft 365 Into a C2 Channel

Cisco Talos details UAT-11587, a China-linked group using the Antino backdoor and Microsoft 365 as cover to spy on Asian governments.

Cisco Talos has been tracking a cluster of espionage activity since September 2025 that it calls UAT-11587, and by July 2026 the group had hit at least 16 government and policy organizations across eight Asian countries. The toolset includes a previously undocumented backdoor Talos named Antino, and the thing that makes it worth paying attention to isn’t how it gets in. It’s where it hides once it’s there.

Antino is written in Rust and works on both 32-bit and 64-bit versions of Windows. It supports the usual backdoor features, including shell and PowerShell access, file transfers, in-memory shellcode execution and persistence.