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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:1
class ShellOPSEC(CommandOPSEC):
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injection_method = ""
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process_creation = "/bin/bash -c"
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authentication = ""
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​
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async def opsec_pre(self, task: MythicTask):
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​
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processes = await MythicResponseRPC(task).search_database(
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table="process",
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search={"host": task.callback.host}
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)
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if len(processes.response) == 0:
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task.opsec_pre_blocked = True
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task.opsec_pre_message = f"This spawns {self.process_creation} and there is no process data on the host yet."
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task.opsec_pre_message += "\nRun \"list_apps\" first to check for dangerous processes"
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task.opsec_pre_bypass_role = "operator"
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return
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else:
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processes = await MythicResponseRPC(task).search_database(
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table="process",
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search={"name": "Microsoft Defender", "host": task.callback.host}
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)
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if len(processes.response) > 0:
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task.opsec_pre_blocked = True
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task.opsec_pre_message = f"Microsoft Defender spotted on the host in running processes. Don't spawn commands this way"
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​
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async def opsec_post(self, task: MythicTask):
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processes = await MythicResponseRPC(task).search_database(
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table="process",
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search={"name": "Microsoft Defender", "host": task.callback.host}
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)
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if len(processes.response) > 0:
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task.opsec_post_blocked = True
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task.opsec_post_message = f"Microsoft Defender spotted on the host in running processes. Really, don't do this"
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class ShellCommand(CommandBase):
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cmd = "shell"
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needs_admin = False
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help_cmd = "shell {command}"
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description = """This runs {command} in a terminal by leveraging JXA's Application.doShellScript({command}).
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WARNING! THIS IS SINGLE THREADED, IF YOUR COMMAND HANGS, THE AGENT HANGS!"""
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version = 1
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is_exit = False
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is_file_browse = False
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is_process_list = False
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is_download_file = False
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is_remove_file = False
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is_upload_file = False
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author = "@its_a_feature_"
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attackmapping = ["T1059"]
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argument_class = ShellArguments
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opsec_class = ShellOPSEC
Copied!
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 classopsec_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 notopsec_pre/post_message- this is the message to the operator about the result of doing this OPSEC checkopsec_pre/post_bypass_role- this determines who should be able to bypass this check. The default isleadto indicate that only the lead of the operation should be able to bypass it, but you can set it tooperatorto 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. Last modified 10mo ago