Detection: AWS Password Policy Changes

Updated Date: 2024-05-10 ID: aee4a575-7064-4e60-b511-246f9baf9895 Author: Bhavin Patel, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects successful API calls to view, update, or delete the password policy in an AWS organization. It leverages AWS CloudTrail logs to identify events such as "UpdateAccountPasswordPolicy," "GetAccountPasswordPolicy," and "DeleteAccountPasswordPolicy." This activity is significant because it is uncommon for regular users to perform these actions, and such changes can indicate an adversary attempting to understand or weaken password defenses. If confirmed malicious, this could lead to compromised accounts and increased attack surface, potentially allowing unauthorized access and control over AWS resources.

1`cloudtrail` eventName IN ("UpdateAccountPasswordPolicy","GetAccountPasswordPolicy","DeleteAccountPasswordPolicy") errorCode=success 
2| stats count values(eventName) as eventName values(userAgent) min(_time) as firstTime max(_time) as lastTime by eventSource aws_account_id errorCode  awsRegion userIdentity.principalId user_arn src_ip 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)`  
5| `aws_password_policy_changes_filter`

Data Source

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

Macros Used

Name Value
cloudtrail sourcetype=aws:cloudtrail
aws_password_policy_changes_filter search *
aws_password_policy_changes_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
T1201 Password Policy Discovery Discovery
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
Chimera
OilRig
Turla

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

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 triggered an AWS audit tool activity which may trigger this event.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
User $user_arn$ is attempting to $eventName$ the password policy for account id $aws_account_id$ 72 90 80
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