Detection: AWS IAM Delete Policy

Updated Date: 2024-05-27 ID: ec3a9362-92fe-11eb-99d0-acde48001122 Author: Michael Haag, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the deletion of an IAM policy in AWS. It leverages AWS CloudTrail logs to identify DeletePolicy events, excluding those from AWS internal services. This activity is significant as unauthorized policy deletions can disrupt access controls and weaken security postures. If confirmed malicious, an attacker could remove critical security policies, potentially leading to privilege escalation, unauthorized access, or data exfiltration. Monitoring this behavior helps ensure that only authorized changes are made to IAM policies, maintaining the integrity and security of the AWS environment.

Search

1`cloudtrail` eventName=DeletePolicy (userAgent!=*.amazonaws.com) 
2| stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.policyArn) as policyArn by src user_arn eventName eventSource aws_account_id errorCode errorMessage userAgent eventID awsRegion userIdentity.principalId 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `aws_iam_delete_policy_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
AWS CloudTrail DeletePolicy	AWS	`'aws:cloudtrail'`	`'aws_cloudtrail'`	N/A

Macros Used

Name	Value
cloudtrail	`sourcetype=aws:cloudtrail`
aws_iam_delete_policy_filter	`search *`

aws_iam_delete_policy_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
T1098	Account Manipulation	Persistence

KillChainPhase.EXPLOITAITON

KillChainPhase.INSTALLATION

NistCategory.DE_AE

Cis18Value.CIS_10

APT3

APT41

APT5

Dragonfly

FIN13

HAFNIUM

Kimsuky

Lazarus Group

Magic Hound

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 Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

The Splunk AWS Add-on and Splunk App for AWS is required to utilize this data. The search requires AWS CloudTrail logs.

Known False Positives

This detection will require tuning to provide high fidelity detection capabilties. Tune based on src addresses (corporate offices, VPN terminations) or by groups of users. Not every user with AWS access should have permission to delete policies (least privilege). In addition, this may be saved seperately and tuned for failed or success attempts only.

Associated Analytic Story

AWS IAM Privilege Escalation

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
User $user_arn$ has deleted AWS Policies from IP address $src$ by executing the following command $eventName$	10	20	50

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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: 2