Detection: AWS Defense Evasion Impair Security Services

Description

The following analytic detects attempts to delete critical AWS security service configurations, such as CloudWatch alarms, GuardDuty detectors, and Web Application Firewall rules. It leverages CloudTrail logs to identify specific API calls like "DeleteLogStream" and "DeleteDetector." This activity is significant because it indicates potential efforts to disable security monitoring and evade detection. If confirmed malicious, this could allow attackers to operate undetected, escalate privileges, or exfiltrate data without triggering security alerts, severely compromising the security posture of the AWS environment.

1`cloudtrail` eventName IN ("DeleteLogStream","DeleteDetector","DeleteIPSet","DeleteWebACL","DeleteRule","DeleteRuleGroup","DeleteLoggingConfiguration","DeleteAlarms") 
2| stats count min(_time) as firstTime max(_time) as lastTime values(eventName)  as eventName values(eventSource) as eventSource values(requestParameters.*) as * by src region user_arn aws_account_id user_type user_agent errorCode
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)`
5|  `aws_defense_evasion_impair_security_services_filter`

Data Source

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

Macros Used

Name Value
cloudtrail sourcetype=aws:cloudtrail
aws_defense_evasion_impair_security_services_filter search *
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

You must install Splunk AWS Add on and enable CloudTrail logs in your AWS Environment.

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

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
User $user_arn$ has made potentially risky api calls $eventName$ 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_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