Detection: ASL AWS Defense Evasion PutBucketLifecycle

Updated Date: 2024-12-16 ID: 986565a2-7707-48ea-9590-37929cebc938 Author: Patrick Bareiss, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects PutBucketLifecycle events in AWS CloudTrail logs where a user sets a lifecycle rule for an S3 bucket with an expiration period of fewer than three days. This detection leverages CloudTrail logs to identify suspicious lifecycle configurations. This activity is significant because attackers may use it to delete CloudTrail logs quickly, thereby evading detection and impairing forensic investigations. If confirmed malicious, this could allow attackers to cover their tracks, making it difficult to trace their actions and respond to the breach effectively.

Search

 1`amazon_security_lake` api.operation=PutBucketLifecycle 
 2| spath input=api.request.data path=LifecycleConfiguration.Rule.NoncurrentVersionExpiration.NoncurrentDays output=NoncurrentDays 
 3| where NoncurrentDays < 3 
 4| spath input=api.request.data 
 5| fillnull 
 6| stats count min(_time) as firstTime max(_time) as lastTime by api.operation actor.user.uid actor.user.account.uid http_request.user_agent src_endpoint.ip cloud.region NoncurrentDays bucketName 
 7| rename actor.user.uid as user, src_endpoint.ip as src_ip, cloud.region as region, http_request.user_agent as user_agent 
 8| `security_content_ctime(firstTime)` 
 9|  `security_content_ctime(lastTime)` 
10| `asl_aws_defense_evasion_putbucketlifecycle_filter`

Data Source

Name	Platform	Sourcetype	Source
ASL AWS CloudTrail	AWS	`'aws:asl'`	`'aws_asl'`

Macros Used

Name	Value
amazon_security_lake	`sourcetype=aws:asl`
asl_aws_defense_evasion_putbucketlifecycle_filter	`search *`

asl_aws_defense_evasion_putbucketlifecycle_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
T1562.008	Disable or Modify Cloud Logs	Defense Evasion
T1562	Impair Defenses	Defense Evasion
T1485.001	Lifecycle-Triggered Deletion	Impact
T1485	Data Destruction	Impact

Actions on Objectives

Exploitation

DE.AE

CIS 10

APT29

Magic Hound

APT38

LAPSUS$

Lazarus Group

Sandworm Team

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 detection is based on Amazon Security Lake events from Amazon Web Services (AWS), which is a centralized data lake that provides security-related data from AWS services. To use this detection, you must ingest CloudTrail logs from Amazon Security Lake into Splunk. To run this search, ensure that you ingest events using the latest version of Splunk Add-on for Amazon Web Services (https://splunkbase.splunk.com/app/1876) or the Federated Analytics App.

Known False Positives

While this search has no known false positives, it is possible that it is a legitimate admin activity. Please consider filtering out these noisy events using userAgent, user_arn field names.

Associated Analytic Story

AWS Defense Evasion

References

https://stratus-red-team.cloud/attack-techniques/AWS/aws.defense-evasion.cloudtrail-lifecycle-rule/

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`aws_asl`	`aws:asl`
Integration	✅ Passing	Dataset	`aws_asl`	`aws:asl`

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: 1