Detection rules › YARA-L

AWS GuardDuty Disabled

Severity
high
Type
Alert
Author
Google Cloud Security
Source
github.com/chronicle/detection-rules

Detects when a GuardDuty Detector is disabled or suspended.

MITRE ATT&CK coverage

TacticTechniques
StealthT1562 Impair Defenses

Event coverage

Rule body yaral

/*
 * Copyright 2023 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

rule aws_guardduty_disabled {

  meta:
    author = "Google Cloud Security"
    description = "Detects when a GuardDuty Detector is disabled or suspended."
    rule_id = "mr_22495d55-4177-425f-9a4e-8d836b01e976"
    rule_name = "AWS GuardDuty Disabled"
    mitre_attack_tactic = "Defense Evasion"
    mitre_attack_technique = "Impair Defenses"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1562/"
    mitre_attack_version = "v13.1"
    type = "Alert"
    data_source = "AWS CloudTrail"
    platform = "AWS"
    severity = "High"
    priority = "High"

  events:
    $cloudtrail.metadata.vendor_name = "AMAZON"
    $cloudtrail.metadata.product_name = "AWS CloudTrail"
    $cloudtrail.metadata.product_event_type = "DeleteDetector" or
    ($cloudtrail.metadata.product_event_type = "UpdateDetector" and $cloudtrail.target.resource.attribute.labels["enable"] = "false")
    $cloudtrail.security_result.action = "ALLOW"

  outcome:
    $risk_score = max(75)
    $mitre_attack_tactic = "Defense Evasion"
    $mitre_attack_technique = "Impair Defenses"
    $mitre_attack_technique_id = "T1562"
    $event_count = count_distinct($cloudtrail.metadata.id)
    $network_http_user_agent = $cloudtrail.network.http.user_agent
    $principal_ip = array_distinct($cloudtrail.principal.ip)
    $principal_ip_country = array_distinct($cloudtrail.principal.ip_geo_artifact.location.country_or_region)
    $principal_ip_state = array_distinct($cloudtrail.principal.ip_geo_artifact.location.state)
    $principal_user_display_name = $cloudtrail.principal.user.user_display_name
    $recipient_aws_account_id = $cloudtrail.additional.fields["recipientAccountId"]
    $aws_region = $cloudtrail.principal.location.name
    $target_resource_name = $cloudtrail.target.resource.name
    $target_resource_product_object_id = $cloudtrail.target.resource.product_object_id

  condition:
    $cloudtrail
}

Detection logic

Fires when at least one $cloudtrail event.

Events

$cloudtrail

  • metadata.product_event_type = "DeleteDetector"
  • metadata.product_event_type = "UpdateDetector"
  • target.resource.attribute.labels["enable"] = "false"
  • security_result.action = "ALLOW"

Outcome

Fields the detection emits on a match. $risk_score drives alerting; Chronicle surfaces the rest on the detection.

FieldExpression
risk_scoremax(75)
event_countcount_distinct($cloudtrail.metadata.id)
network_http_user_agent$cloudtrail.network.http.user_agent
principal_iparray_distinct($cloudtrail.principal.ip)
principal_ip_countryarray_distinct($cloudtrail.principal.ip_geo_artifact.location.country_or_region)
principal_ip_statearray_distinct($cloudtrail.principal.ip_geo_artifact.location.state)
principal_user_display_name$cloudtrail.principal.user.user_display_name
recipient_aws_account_id$cloudtrail.additional.fields["recipientAccountId"]
aws_region$cloudtrail.principal.location.name
target_resource_name$cloudtrail.target.resource.name
target_resource_product_object_id$cloudtrail.target.resource.product_object_id