Detection on Alternate Targets

Detection & Response rules run against edr events by default, however, there are 7 other targets:

• detection

• deployment

• artifact

• artifact_event

• schedule

• audit

• billing

This article is to give some ideas of what they're used for, and how they're used.

Target: detection

You can run rules on detections generated by other rules. This allows you to further filter existing detections
and change add a response behavior to certain special cases.

In the detection target, the event: or events: specified refer to the name of the detection specified in the
original detection's report action.

The detection target supports all of the same operators and actions as regular edr rules.

Example

# Detection
target: detection
op: and
rules:
- op: is
  path: cat
  value: virus-total-hit
- op: is
  path: routing/hostname
  value: ceo-laptop

# Response
- action: extension request
  extension name: pagerduty
  extension action: run
  request:
    group: '{{ "lc-alerts" }}'
    severity: '{{ "critical" }}'
    component: '{{ "vip-alert" }}'
    summary: '{{ "Alert on a VIP endpoint." }}'
    source: '{{ "limacharlie.io" }}'
    class: '{{ "dr-rules" }}'

This rule takes a pre-existing detection report named virus-total-hit and sends it to PagerDuty if it occurs on a specific hostname.

Target: deployment

Deployment events relate to sensors connecting to the cloud: enrollment, sensor_clone, sensor_over_quota, deleted_sensor.

Take the sensor_clone event as an example. This event can happen when a Sensor is installed in a VM image, leading to duplicate sensor IDs connecting to the cloud. When this is detected we can use this event to automate behavior to de-duplicate the sensor.

The deployment target supports all of the same operators and actions as regular edr rules.

Example

# Detection
target: deployment
event: sensor_clone
op: is windows

# Response
- action: task
  command: file_del %windir%\system32\hcp.dat
- action: task
  command: file_del %windir%\system32\hcp_hbs.dat
- action: task
  command: file_del %windir%\system32\hcp_conf.dat
- action: task
  command: restart

This rule de-duplicates sensors on Windows by deleting .dat files specific to the Windows installation and then issuing a restart sensor command.

For samples of each deployment event type, see Reference: Platform Events.

Target: artifact

Parsed artifacts can be run through the rule engine as if they were regular edr events, but there are some key differences. Namely, they support a subset of operators and actions, while adding some special parameters.

Example

This rule will target parsed /var/log/auth.log entries to see if there are are auth failures.

# Detection
target: artifact
artifact type: txt
artifact path: /var/log/auth.log
op: matches
re: .*(authentication failure|Failed password).*
path: /text
case sensitive: false

# Response
- action: report
  name: Failed Auth

Supported Operators

• is

• and

• or

• exists

• contains

• starts with

• ends with

• is greater than

• is lower than

• matches

• string distance

Supported Resources

lookup and external resources are supported within rules just like the edr target.

Supported Actions

The only response action supported for the artifact target is the report action.

Special Parameters

• artifact path: matches the start of the artifact's path string, e.g. /auth.log

• artifact type: matches the artifact's type string, e.g. pcap, zeek, auth, wel

• artifact source: matches the artifact's source string, e.g. hostname-123

Note: for duplicate Windows Event Log ingestions, the rule engine will use the log's EventRecordID to ensure a rule will not run more than once over the same record.

Target: artifact_event

For unparsed logs, it can be useful to use the ingest and export_complete lifecycle events from the artifact_event target to automate behaviors in response to artifacts.

For samples of ingest and export_complete, see Reference: Platform Events.

Example

# Detection
target: artifact_event
event: export_complete
op: starts with
path: routing/log_type
value: pcap
case sensitive: false

# Response
- action: report
  name: PCAP Artifact ready to Download

Target: schedule

Schedule events are triggered automatically at various intervals per Organization or per Sensor, observable in rules via the schedule target.

For more information, see Reference: Schedule Events

Target: audit

Audit events are generated by the LimaCharlie platform and track changes and events from within the platform such as tasking, replays, hive changes, etc. These events can be viewed within the "Platform Logs" menu or by viewing events from the audit-logs sensor.

Target: billing

Billing events are generated by the LimaCharlie platform and are related to aspects of the platform such as quotas, thresholds, and other cost-associated events. For an example, see the Usage Alerts Extension documentation