AWS SAML Identity Provider Changes

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

Detects create, update or delete events of a SAML provider in AWS.

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1078` Valid Accounts
Persistence	`T1078` Valid Accounts
Privilege Escalation	`T1078` Valid Accounts
Stealth	`T1078` Valid Accounts

Telemetry coverage

Platform	Record / event type
AWS	CloudTrail event `CreateSAMLProvider`: Creates an IAM resource that describes an identity provider supporting SAML 2.0, enabling federated users to sign in to AWS.
AWS	CloudTrail event `DeleteSAMLProvider`: Deletes a SAML provider resource object in IAM, removing the federated identity configuration.
AWS	CloudTrail event `UpdateSAMLProvider`: Updates the metadata document for an existing SAML provider in IAM.

Rule body

// Copyright 2023 Google LLC. Licensed under Apache-2.0.

rule aws_saml_identity_provider_changes {

  meta:
    author = "Google Cloud Security"
    description = "Detects create, update or delete events of a SAML provider in AWS."
    rule_id = "mr_2f36760a-241d-4ace-9142-db0ccf1992b7"
    rule_name = "AWS SAML Identity Provider Changes"
    mitre_attack_tactic = "Defense Evasion, Persistence, Privilege Escalation, Initial Access"
    mitre_attack_technique = "Valid Accounts"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1078/"
    mitre_attack_version = "v13.1"
    type = "Alert"
    data_source = "AWS CloudTrail"
    platform = "AWS"
    severity = "Medium"
    priority = "Medium"

  events:
    $cloudtrail.metadata.vendor_name = "AMAZON"
    $cloudtrail.metadata.product_name = "AWS CloudTrail"
    (
      $cloudtrail.metadata.product_event_type = "CreateSAMLProvider" or
      $cloudtrail.metadata.product_event_type = "UpdateSAMLProvider" or
      $cloudtrail.metadata.product_event_type = "DeleteSAMLProvider"
    )
    $cloudtrail.security_result.action = "ALLOW"

  outcome:
    $risk_score = max(50)
    $mitre_attack_tactic = "Defense Evasion, Persistence, Privilege Escalation, Initial Access"
    $mitre_attack_technique = "Valid Accounts"
    $mitre_attack_technique_id = "T1078"
    $event_count = count_distinct($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
}

YARA-L rule structure

Condition

Fires when at least one $cloudtrail event.

Events

`$cloudtrail`

metadata.product_event_type is one of:
- CreateSAMLProvider
- UpdateSAMLProvider
- DeleteSAMLProvider
security_result.action = "ALLOW"

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(50)`
`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`