Detection: AWS Create Policy Version to allow all resources

Updated Date: 2025-02-10 ID: 2a9b80d3-6340-4345-b5ad-212bf3d0dac4 Author: Bhavin Patel, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies the creation of a new AWS IAM policy version that allows access to all resources. It detects this activity by analyzing AWS CloudTrail logs for the CreatePolicyVersion event with a policy document that grants broad permissions. This behavior is significant because it violates the principle of least privilege, potentially exposing the environment to misuse or abuse. If confirmed malicious, an attacker could gain extensive access to AWS resources, leading to unauthorized actions, data exfiltration, or further compromise of the AWS environment.

 1`cloudtrail` eventName=CreatePolicyVersion eventSource = iam.amazonaws.com errorCode = success 
 2| spath input=requestParameters.policyDocument output=key_policy_statements path=Statement{} 
 3| mvexpand key_policy_statements 
 4| spath input=key_policy_statements output=key_policy_action_1 path=Action 
 5| where key_policy_action_1 = "*" 
 6| rename user_name as user 
 7| stats count min(_time) as firstTime max(_time) as lastTime values(key_policy_statements) as policy_added by signature dest user user_agent src vendor_account vendor_region vendor_product 
 8| `security_content_ctime(firstTime)` 
 9| `security_content_ctime(lastTime)` 
10|`aws_create_policy_version_to_allow_all_resources_filter`

Data Source

Name Platform Sourcetype Source
AWS CloudTrail CreatePolicyVersion AWS icon AWS 'aws:cloudtrail' 'aws_cloudtrail'

Macros Used

Name Value
cloudtrail sourcetype=aws:cloudtrail
aws_create_policy_version_to_allow_all_resources_filter search *
aws_create_policy_version_to_allow_all_resources_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1078.004 Cloud Accounts Defense Evasion
Delivery
Exploitation
Installation
DE.CM
CIS 13

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs.

Known False Positives

While this search has no known false positives, it is possible that an AWS admin has legitimately created a policy to allow a user to access all resources. That said, AWS strongly advises against granting full control to all AWS resources and you must verify this activity.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

User $user$ created a policy version that allows them to access any resource in their account.

Risk Object Risk Object Type Risk Score Threat Objects
user user 49 No Threat Objects

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset aws_cloudtrail aws:cloudtrail
Integration ✅ Passing Dataset aws_cloudtrail aws:cloudtrail

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 9