AWS IAM Inline Policy Added to a Group

[metadata]
creation_date = "2026/06/18"
integration = ["aws"]
maturity = "production"
updated_date = "2026/06/18"

[rule]
author = ["Elastic"]
description = """
Identifies an inline policy added to an IAM group via PutGroupPolicy. An inline policy attached to a group grants its
permissions to every current and future member of that group. Adversaries can abuse this to escalate privileges (grant
elevated permissions to a group they belong to, or will add themselves to) and to establish persistence through a
durable, membership-based grant that is easy to overlook. Group inline policies are uncommon compared to managed-policy
attachments, so their creation by an unexpected principal warrants review.
"""
false_positives = [
    """
    Identity and platform teams and infrastructure-as-code pipelines occasionally manage group inline policies as part
    of normal access governance. Verify the principal in `aws.cloudtrail.user_identity.arn`, the targeted group, and the
    policy document against approved change records. Known administration roles and deployment automation can be
    excluded after validation.
    """,
]
from = "now-6m"
index = ["logs-aws.cloudtrail-*"]
language = "kuery"
license = "Elastic License v2"
name = "AWS IAM Inline Policy Added to a Group"
note = """## Triage and analysis

### Investigating AWS IAM Inline Policy Added to a Group

`PutGroupPolicy` embeds an inline permissions policy directly on an IAM group. Because the policy applies to all members of the group, it is an effective way to broadly grant permissions — and, for an adversary, to escalate privileges or persist while drawing less attention than attaching a well-known managed policy such as `AdministratorAccess`. Group inline policies are relatively rare, which makes their creation a useful signal.

### Possible investigation steps

- Identify the actor in `aws.cloudtrail.user_identity.arn`, `aws.cloudtrail.user_identity.type`, and `aws.cloudtrail.user_identity.session_context.session_issuer.arn`, and review `source.ip` / `user_agent.original` to determine how the change was made.
- Inspect `aws.cloudtrail.request_parameters` for the targeted `groupName`, the `policyName`, and the `policyDocument` to assess what permissions were granted (look for broad `Action`/`Resource` of `*`, IAM, or data-access permissions).
- Enumerate the group's current members to understand who immediately gains the new permissions, and whether the actor is or could become a member.
- Confirm whether the change aligns with an approved access request, onboarding, or deployment.
- Correlate with recent activity by the same principal, such as group creation, adding users to the group, or other IAM modifications that may form an escalation chain.

### False positive analysis

- Approved access governance and infrastructure-as-code may add group inline policies. Confirm the change is expected and exclude known administration roles or automation on `aws.cloudtrail.user_identity.arn` after validation.

### Response and remediation

- If the change is unauthorized, remove the inline policy from the group (`DeleteGroupPolicy`) and review which members used the granted permissions while it was in place.
- Rotate or restrict credentials for the principal if compromise is suspected, and constrain `iam:PutGroupPolicy` to a small set of trusted administrators.

### Additional information

- [IAM identity-based policies (inline)](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_managed-vs-inline.html)
- [PutGroupPolicy API](https://docs.aws.amazon.com/IAM/latest/APIReference/API_PutGroupPolicy.html)
"""
references = [
    "https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_managed-vs-inline.html",
    "https://docs.aws.amazon.com/IAM/latest/APIReference/API_PutGroupPolicy.html",
]
risk_score = 47
rule_id = "87f8141e-4275-4d49-9e76-d215b4614a0b"
severity = "medium"
tags = [
    "Domain: Cloud",
    "Domain: Identity",
    "Data Source: AWS",
    "Data Source: Amazon Web Services",
    "Data Source: AWS IAM",
    "Use Case: Threat Detection",
    "Tactic: Privilege Escalation",
    "Tactic: Persistence",
    "Resources: Investigation Guide",
]
timestamp_override = "event.ingested"
type = "query"

query = '''
data_stream.dataset: "aws.cloudtrail"
    and event.provider: "iam.amazonaws.com"
    and event.action: "PutGroupPolicy"
    and event.outcome: "success"
    and not aws.cloudtrail.user_identity.type: "AWSService"
    and not user_agent.original: (*terraform* or *pulumi* or *ansible*)
    and not aws.cloudtrail.user_identity.arn: (*terraform* or *pulumi* or *ansible*)
    and not source.as.organization.name: (Amazon* or AMAZON* or Google*)
    and not source.address: ("cloudformation.amazonaws.com" or "servicecatalog.amazonaws.com")
'''


[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1098"
name = "Account Manipulation"
reference = "https://attack.mitre.org/techniques/T1098/"

[rule.threat.tactic]
id = "TA0004"
name = "Privilege Escalation"
reference = "https://attack.mitre.org/tactics/TA0004/"

[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1098"
name = "Account Manipulation"
reference = "https://attack.mitre.org/techniques/T1098/"
[[rule.threat.technique.subtechnique]]
id = "T1098.003"
name = "Additional Cloud Roles"
reference = "https://attack.mitre.org/techniques/T1098/003/"
[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"

[rule.investigation_fields]
field_names = [
    "@timestamp",
    "user.name",
    "user_agent.original",
    "source.ip",
    "aws.cloudtrail.user_identity.arn",
    "aws.cloudtrail.user_identity.type",
    "aws.cloudtrail.user_identity.access_key_id",
    "aws.cloudtrail.user_identity.session_context.session_issuer.arn",
    "aws.cloudtrail.request_parameters",
    "aws.cloudtrail.response_elements",
    "event.action",
    "event.outcome",
    "cloud.account.id",
    "cloud.region",
]