Medusa

Medusa is a cross-platform agent compatible with both Python 3.8 and Python 2.7.

Installation

To install Medusa, you'll need Mythic v3 installed on a remote computer. You can find installation instructions for Mythic at the Mythic project page.

From the Mythic install root, run the command:

./mythic-cli install github https://github.com/MythicAgents/Medusa.git

Once installed, restart Mythic to build a new agent.

Notable Features

• Dynamic loading/unloading of agent functions to limit exposure of agent capabilities on-disk.
• Loading of Python modules in-memory for use in custom scripts.
• Cross-platform SOCKS5 proxy
• macOS clipboard reader, screenshot grabber and TCC database parsing
• File browser compatibility with upload/download
• Eval() of dynamic Python code
• Basic Authentication Proxy compatibility

Commands Manual Quick Reference

The base agent and included commands all use built-in Python libraries, so do not need additional packages to function. Agents will run the commands in threads, so long-running uploads or downloads won't block the main agent.

General Commands

macOS Commands

Windows Commands

Python Versions

Both versions of the Medusa agent use an AES256 HMAC implementation written with built-in libraries (adapted from here), removing the need for any additional dependencies beyond a standard Python install. As such the agent should operate across Windows, Linux and macOS hosts. It's worth mentioning that this crypto implementation does introduce some overhead when handling large files (screenshotting, downloads, etc.) but it's workable.

Py2 vs Py3 Commands

Within the Payload_Type/Medusa/agent_code directory, you will see base_agent files with both py2 and py3 suffixes. Likewise, similar file extensions can be seen for individual function files too.

These are read by the builder.py script to firstly select the right base Python version of the Medusa agent. builder.py will then include commands that are specific to the chosen python version. In the case where a command only has a .py extension, this will be used by default, with the assumption being that no alternative code is needed between the Py2 and Py3 versions.

Threaded Jobs

Medusa uses basic threading for job execution. Where jobs are potentially long-running, they can be implemented with a 'stop check' to respond to a signal from the jobkill task. This can be implemented with a code snippet similar to that shown below:

if [task for task in self.taskings if task["task_id"] == task_id][0]["stopped"]:
  # Some job-specific tidy up
  return "Job stopped."

This handler can be seen implemented within the download, upload, watch_dir and screenshot commands.

Additionally, if the long-running job is expected to provide continuous output, the sendTaskOutputUpdate function - included in the base agent - can be used to update Mythic prior to the task completion. A dummy function that provides continuous output and can be jobkill'd can be seen below.

def dummyFunction(self, task_id):
  while(True):
      # Check if we've got a stop signal.
      if [task for task in self.taskings if task["task_id"] == task_id][0]["stopped"]: return "Job stopped."
      
      # Send output back to Mythic
      self.sendTaskOutputUpdate(task_id, "We're still running")

      time.sleep(10)

Supported C2 Profiles

Currently, only one C2 profile is available to use when creating a new Medusa agent: http (both with and without AES256 HMAC encryption).

HTTP Profile

The HTTP profile calls back to the Mythic server over the basic, non-dynamic profile. GET requests for taskings, POST requests with responses.

Thanks

• Browser scripts and agent code adapted from @its_a_feature_ and @djhohnstein.
• MacC2 and this blog post from Cedric Owens
• EmPyre and this blog post from Chris Ross.
• The crypto wizardry found here.
• Agent icon from flaticon.com