How it works

When is an active response triggered?

An active response is a script that is configured to execute when a specific alert, alert level, or rule group has been triggered. Active responses are either stateful or stateless responses.

• Stateful. Are configured to undo the action after a specified period of time.

• Stateless. Are configured as one-time actions without an event to revert the original effect.

Where are active response actions executed?

Each active response specifies where its associated command will be executed: on the agent that triggered the alert, on the manager, on another specified agent or on all agents, which also includes the manager(s). The location options are:

• Local. It runs the script on the agent that generated the alert.

• Server. It runs the script on the Wazuh manager.

• Defined agent. It specifies the IDs of the agents that run the script regardless of where the event has been observed.

• All. Every agent in the environment will run the script. Use with caution.

Active response configuration

Active responses are configured in the manager by modifying the ossec.conf file as follows:

1. Create a command

   In order to configure an active response, a command must be defined that will initiate a certain script in response to a trigger.

   To configure the active response, define the name of a command using the pattern below and then reference the script to be initiated.

   Example:

   <command>
     <name>host-deny</name>
     <executable>host-deny</executable>
     <timeout_allowed>yes</timeout_allowed>
   </command>
   

   In this example, the command is called host-deny and initiates the host-deny script. This command is configured to allow a timeout after a specified period of time, making it a stateful response.

   Note

   More information and options to create a command here: command

2. Define the active response

   The active response configuration defines when and where a command is going to be executed. A command will be triggered when a specific rule with a specific id, severity level or source matches the active response criteria. This configuration will further define where the action of the command will be initiated, meaning in which environment (agent, manager, local, or everywhere).

   Example:

   <active-response>
     <command>host-deny</command>
     <location>local</location>
     <level>7</level>
     <timeout>600</timeout>
   </active-response>
   

   In this example, the active response is configured to execute the command that was defined in the previous step. The where of the action is defined as the local host and the when is defined as any time the rule has a level higher than 6. The timeout that was allowed in the command configuration is also defined in the above example.

The active response log can be viewed at /var/ossec/logs/active-responses.log.

Default Active response scripts

Wazuh is preconfigured with the following scripts for Linux, located at /var/ossec/active-response/bin. Click each script name to see its source code.

The following preconfigured scripts for Windows are located at C:\Program Files\ossec-agent\active-response\bin. Click each script name to see its source code.