Detection: ASL AWS Defense Evasion Impair Security Services

Updated Date: 2024-05-13 ID: 5029b681-0462-47b7-82e7-f7e3d37f5a2d Author: Patrick Bareiss, Bhavin Patel, Gowthamaraj Rajendran, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the deletion of critical AWS Security Services configurations, such as CloudWatch alarms, GuardDuty detectors, and Web Application Firewall rules. It leverages Amazon Security Lake logs to identify specific API calls like "DeleteLogStream" and "DeleteDetector." This activity is significant because adversaries often use these actions to disable security monitoring and evade detection. If confirmed malicious, this could allow attackers to operate undetected, leading to potential data breaches, unauthorized access, and prolonged persistence within the AWS environment.

Search

1`amazon_security_lake` api.operation IN ("DeleteLogStream","DeleteDetector","DeleteIPSet","DeleteWebACL","DeleteRule","DeleteRuleGroup","DeleteLoggingConfiguration","DeleteAlarms") 
2| fillnull 
3| stats count min(_time) as firstTime max(_time) as lastTime by api.operation actor.user.account_uid actor.user.uid http_request.user_agent src_endpoint.ip cloud.region 
4| rename actor.user.uid as user, src_endpoint.ip as src_ip, cloud.region as region, http_request.user_agent as user_agent, actor.user.account_uid as aws_account_id 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `asl_aws_defense_evasion_impair_security_services_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
N/A	N/A	N/A	N/A	N/A

Macros Used

Name	Value
amazon_security_lake	`sourcetype=aws:cloudtrail:lake`
asl_aws_defense_evasion_impair_security_services_filter	`search *`

asl_aws_defense_evasion_impair_security_services_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

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT29

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 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

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
User $user$ has made potentially risky api calls $api.operation$ that could impair AWS security services for account id $aws_account_id$	42	70	60

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_asl`	`aws:cloudtrail:lake`
Integration	✅ Passing	Dataset	`aws_asl`	`aws:cloudtrail:lake`

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: 3