The SOMBRAT backdoor is packaged as a 64-bit Windows executable. It communicates with a configurable command and control (C2) server via multiple protocols, including DNS, TLS-encrypted TCP, and potentially WebSockets. The backdoor's primary purpose is to download and execute plugins provided via the C2 server. In contrast to the SOMBRAT version published in November 2020, Mandiant observed additional obfuscation and armoring to evade detection, this SOMBRAT variant has been hardened to discourage analysis. Program metadata typically included by the compiler has been stripped and strings have been inlined and encoded via XOR-based routines