OPSEC Checking

What is OPSEC Checking

It's often useful to perform some operational security checks before issuing a task based on everything you know so far, or after you've generated new artifacts for a task but before an agent picks it up. This allows us to be more granular and context aware instead of the blanket command blocking that's available from the Operation Management page in Mythic.

Where is OPSEC Checking?

OPSEC checks and information for a command is located in the same file where everything else for the command is located. We'll be tracking this data with a new class called CommandOPSEC . Let's take an example all the way through:

class ShellOPSEC(CommandOPSEC):
injection_method = ""
process_creation = "/bin/bash -c"
authentication = ""
async def opsec_pre(self, task: MythicTask):
processes = await MythicResponseRPC(task).search_database(
table="process",
search={"host": task.callback.host}
)
if len(processes.response) == 0:
task.opsec_pre_blocked = True
task.opsec_pre_message = f"This spawns {self.process_creation} and there is no process data on the host yet."
task.opsec_pre_message += "\nRun \"list_apps\" first to check for dangerous processes"
task.opsec_pre_bypass_role = "operator"
return
else:
processes = await MythicResponseRPC(task).search_database(
table="process",
search={"name": "Microsoft Defender", "host": task.callback.host}
)
if len(processes.response) > 0:
task.opsec_pre_blocked = True
task.opsec_pre_message = f"Microsoft Defender spotted on the host in running processes. Don't spawn commands this way"
async def opsec_post(self, task: MythicTask):
processes = await MythicResponseRPC(task).search_database(
table="process",
search={"name": "Microsoft Defender", "host": task.callback.host}
)
if len(processes.response) > 0:
task.opsec_post_blocked = True
task.opsec_post_message = f"Microsoft Defender spotted on the host in running processes. Really, don't do this"
class ShellCommand(CommandBase):
cmd = "shell"
needs_admin = False
help_cmd = "shell {command}"
description = """This runs {command} in a terminal by leveraging JXA's Application.doShellScript({command}).
WARNING! THIS IS SINGLE THREADED, IF YOUR COMMAND HANGS, THE AGENT HANGS!"""
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 = "@its_a_feature_"
attackmapping = ["T1059"]
argument_class = ShellArguments
opsec_class = ShellOPSEC

Notice that we hook this OPSEC class instance into our Shell command by adding a new parameter called opsec_class and pointing it at our new OPSEC class

opsec_pre / opsec_post

In the case of doing operational checks before a task's create_tasking is called, we have the opsec_pre function. Similarly, the opsec_post function happens after your create_tasking, but before your task is finally ready for an agent to pick it up.

These functions don't return anything - instead, they modifies properties on the task itself. Specifically, the function can set:

  • opsec_pre/post_blocked - this indicates True/False for if the function decides the task should be blocked or not

  • opsec_pre/post_message - this is the message to the operator about the result of doing this OPSEC check

  • opsec_pre/post_bypass_role - this determines who should be able to bypass this check. The default is lead to indicate that only the lead of the operation should be able to bypass it, but you can set it to operator to allow any operators to bypass the check. This is helpful in cases where it's not necessarily a "block", but something you want to make sure operators acknowledge as a potential security risk

This function takes one argument, the task itself. Just like with the create_tasking function, you get a LOT of context with the task variable (Create_Tasking).

As the name of the functions imply, the opsec_pre check happens before create_tasking function runs and the opsec_post check happens after the create_tasking function runs. If you set opsec_pre_blocked to True, then the create_tasking function isn't executed until an approved operator bypasses the check. Then, execution goes back to create_tasking and the opsec_post. If that one also sets blocked to True, then it's again blocked at the user to bypass it. At this point, if it's bypassed, the task status simply switched to Submitted so that an agent can pick up the task on next checkin.

OPSEC Information Tracking

As part of the CommandOPSEC class, there are a few parameters in addition to the opsec_pre and opsec_post functions. These pieces of information allow us to start tracking what exactly the command is going to do from an OPSEC perspective. Does it inject into another process? Does it spawn processes? Is it going to do any specific kind of authentication (network, new credential, making a token, etc)?

By tracking this information as part of this OPSEC class, we can start making broader checks and more generalized functions to call. Maybe for every command that does process injection, we want to first (as part of an opsec_pre check) check for certain defensive products on the box that might pick up on that type of activity. There's no reason for us to re-write that every time in each function. That leads to fragmented and repeated code. We might also want to check to see if there are any currently running tasks for a specific host that are doing certain kinds of authentication before we allow the current task to inject a kerberos ticket or steal a token.

OPSEC Scripting

From the opsec_pre and opsec_post functions, you have access to the entire task/callback information like you do in Create_Tasking. Additionally, you have access to the entire RPC suite just like in Create_Tasking.