What is openudc2?

OpenUDC2 is an open source, proof-of-concept implementation of a protocol specification called UDC2, which was originally introduced by the commercial security tool Cobalt Strike. UDC2 lets a Cobalt Strike operator plug in custom communication channels, called user-defined command and control, so that the traffic between an implant and its controller can use different transport methods. This project's goal is to let open source command and control frameworks read and use the same UDC2 modules that the Cobalt Strike community already builds, rather than each framework needing its own incompatible plugin format. The proof of concept is built specifically against Adaptix C2, an open source command and control framework, but the author states it does not rely on anything Adaptix-specific and is meant to be portable to other frameworks that support a similar custom agent and listener design. It is implemented as two Adaptix C2 extensions: one is a fork of Adaptix's default beacon agent with added support for the OpenUDC2 protocol, and the other is a listener component that mimics how a Cobalt Strike UDC2 listener behaves. The README is explicit that this proof of concept does not include any additional encryption of its own and that real encryption should be added before any live use. To try it, a user loads both extenders into Adaptix C2, downloads an existing UDC2 module such as the ICMP based one published by Cobalt Strike, creates a UDC2 listener, starts the corresponding server, and generates a beacon that embeds the matching UDC2 module. This project is aimed at security researchers and red team tool developers who already work with C2 frameworks like Adaptix C2 and Cobalt Strike and want to study or extend interoperability between open source and commercial UDC2 style channel plugins in an authorized testing context.