active-response

In the active response configuration section, an existing command is bound to one or more rules or rule types along with additional criteria for when to execute the command. There is no limit to the number of active responses that can be used, however, each active response must be configured in its own separate <active-response> section.

Options

Manager side

Agent side

disabled

Toggles the active-response capability on and off. Setting this option to yes on an agent will disable active-response for that agent only while setting it in the manager ossec.conf file will disable active-response on the manager and all agents.

Note

This option is available on the server, local, and agent installations.

Default value

no

Allowed values

yes, no

command

Links the active-response to the command. You can find more information at the commands section.

Default value

n/a

Allowed values

Any defined active response command name

location

Indicates which system(s) the command should be executed on.

Default value

n/a

Allowed values

local

This runs the command on the agent that generated the event.

server

This runs the command on the ThreatLockDown manager.

defined-agent

This runs the command on a specific agent identified by agent_id.

all

This runs the command on all agents, not including the manager. Use with caution.

Example:

If the application that interfaces with your edge firewall runs on one of your agents, you might have a firewall-block-edge command that runs a script on that agent to blacklist an offending IP address on the edge firewall.

Note

If it is desired to trigger a particular active response on every agent and the manager as well, two similar configuration blocks can be used setting the option "all" in one of the blocks and "server" on the other.

agent_id

Specifies the ID of the agent on which to execute the active response command (used when defined-agent is set).

Default value

n/a

Allowed values

Any agent id number, as long as defined-agent has been specified as the location.

level

Defines a minimum severity level required for the command to be executed.

Default value

n/a

Allowed values

Any level from 1 to 16

rules_group

Defines the rule group that a rule must belong to for the execution of the command.

Default value

n/a

Allowed values

Any group string. For multiple groups, separate the strings with a pipe character |.

Note

To avoid partial matches, add a comma at the end of the group string. For example, <rules_group>group_a,|group_b,|group_c,</rules_group> Also, check that the rule group in your rule definitions ends with a comma as well. This is usually the case in the ThreatLockDown default ruleset. For example, <group>group_b,</group>.

Not ending the group string with a comma implies that the group string is a substring open for partial matches. For example, the group string authentication matches rule groups authentication, authentication_success, and authentication_failure while the group string authentication, matches only rule group authentication.

rules_id

Limits the command execution to only when one or more listed rules fire.

Default value

n/a

Allowed values

Any rule identification. Multiple IDs can be specified if separated by a comma.

Note

When setting level, rules_group, and rules_id together, the active response will be triggered always that any rule matches with one of these options. In other words, they are accumulative options, not restrictive.

timeout

Specifies how long in seconds before the reverse command is executed. When repeated_offenders is used, timeout only applies to the first offense.

Default value

n/a

Allowed values

A positive number (seconds)

repeated_offenders

Sets timeouts in minutes for repeat offenders. This is a comma-separated list of increasing timeouts that can contain a maximum of 5 entries.

Default value

n/a

Allowed values

A positive number (minutes)

Warning

This option must be configured directly in the ossec.conf file of the agent (currently not supported by agents running on Windows), even when using a manager/agent setup with a centralized configuration of other settings via agent.conf. Apart from that, it has to be defined in the upper <active-response> section found in the configuration file.

Sample Configuration

<!-- On the manager side -->

<active-response>
  <disabled>no</disabled>
  <command>host-deny</command>
  <location>defined-agent</location>
  <agent_id>032</agent_id>
  <level>10</level>
  <rules_group>sshd,|pci_dss_11.4,</rules_group>
  <timeout>1</timeout>
</active-response>

<!-- On the agent side -->
<active-response>
  <disabled>no</disabled>
  <repeated_offenders>1,5,10</repeated_offenders>
</active-response>