GCP Multiple Secrets Deleted

Severity: high
Type: Alert
Time window: 1h
Match by: user_id
Author: Google Cloud Security
Source: github.com/chronicle/detection-rules

Detect when multiple secrets or secret versions are deleted from GCP Secret Manager.

MITRE ATT&CK coverage

Tactic	Techniques
Impact	`T1485` Data Destruction

Telemetry coverage

Platform	Record / event type
GCP	google.cloud.secretmanager.SecretManagerService.DeleteSecret: Delete secret
GCP	google.cloud.secretmanager.SecretManagerService.DestroySecretVersion: Destroy secret version

Rule body

// Copyright 2024 Google LLC. Licensed under Apache-2.0.

 rule gcp_multiple_secrets_deleted {

  meta:
    author = "Google Cloud Security"
    description = "Detect when multiple secrets or secret versions are deleted from GCP Secret Manager."
    rule_id = "mr_c91c9fe8-6569-4764-a8d8-9b88dd3b7f77"
    rule_name = "GCP Multiple Secrets Deleted"
    mitre_attack_tactic = "Impact"
    mitre_attack_technique = "Data Destruction"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1485/"
    mitre_attack_version = "v14.1"
    type = "Alert"
    data_source = "GCP Cloud Audit"
    platform = "GCP"
    severity = "High"
    priority = "High"

  events:
    $gcp.metadata.log_type = "GCP_CLOUDAUDIT"
    (
       $gcp.metadata.product_event_type = "google.cloud.secretmanager.v1.SecretManagerService.DestroySecretVersion" or
       $gcp.metadata.product_event_type = "google.cloud.secretmanager.v1.SecretManagerService.DeleteSecret"
    )
    $gcp.target.application = "secretmanager.googleapis.com"
    $gcp.security_result.action = "ALLOW"
    $gcp.target.user.userid = $user_id

  match:
    $user_id over 1h

  outcome:
    $risk_score = max(75)
    $mitre_attack_tactic = "Impact"
    $mitre_attack_technique = "Data Destruction"
    $mitre_attack_technique_id = "T1485"
    $event_count = count_distinct($gcp.metadata.id)
    $network_http_user_agent = array_distinct($gcp.network.http.user_agent)
    $principal_ip = array_distinct($gcp.principal.ip)
    $principal_ip_country = array_distinct($gcp.principal.ip_geo_artifact.location.country_or_region)
    $principal_ip_state = array_distinct($gcp.principal.ip_geo_artifact.location.state)
    $principal_user_id = array_distinct($gcp.principal.user.userid)
    $principal_user_display_name = array_distinct($gcp.principal.user.user_display_name)
    $target_resource_name = array_distinct($gcp.target.resource.name)

  condition:
    #gcp >= 10
}

YARA-L rule structure

Condition

Fires when $gcp occurs at least 10 times in the 1h window.

Events

`$gcp`

metadata.log_type = "GCP_CLOUDAUDIT"
metadata.product_event_type is one of:
- google.cloud.secretmanager.v1.SecretManagerService.DestroySecretVersion
- google.cloud.secretmanager.v1.SecretManagerService.DeleteSecret
target.application = "secretmanager.googleapis.com"
security_result.action = "ALLOW"

Match and correlation

Match key: $user_id (target.user.userid)
Within: 1h

Outcome

Outcome variables add context to a detection. When the rule generates an alert, $risk_score is displayed with it.

Field	Expression
`risk_score`	`max(75)`
`event_count`	`count_distinct($gcp.metadata.id)`
`network_http_user_agent`	`array_distinct($gcp.network.http.user_agent)`
`principal_ip`	`array_distinct($gcp.principal.ip)`
`principal_ip_country`	`array_distinct($gcp.principal.ip_geo_artifact.location.country_or_region)`
`principal_ip_state`	`array_distinct($gcp.principal.ip_geo_artifact.location.state)`
`principal_user_id`	`array_distinct($gcp.principal.user.userid)`
`principal_user_display_name`	`array_distinct($gcp.principal.user.user_display_name)`
`target_resource_name`	`array_distinct($gcp.target.resource.name)`