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Description

This search provides detection of KMS keys where action kms:Encrypt is accessible for everyone (also outside of your organization). This is an indicator that your account is compromised and the attacker uses the encryption key to compromise another company.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2021-01-11
  • Author: Rod Soto, Patrick Bareiss Splunk
  • ID: c79c164f-4b21-4847-98f9-cf6a9f49179e

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1486 Data Encrypted for Impact Impact
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE 


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`cloudtrail` eventName=CreateKey OR eventName=PutKeyPolicy 
| spath input=requestParameters.policy output=key_policy_statements path=Statement{} 
| mvexpand key_policy_statements 
| spath input=key_policy_statements output=key_policy_action_1 path=Action 
| spath input=key_policy_statements output=key_policy_action_2 path=Action{} 
| eval key_policy_action=mvappend(key_policy_action_1, key_policy_action_2) 
| spath input=key_policy_statements output=key_policy_principal path=Principal.AWS 
| search key_policy_action="kms:Encrypt" AND key_policy_principal="*" 
| stats count min(_time) as firstTime max(_time) as lastTime by eventName eventSource eventID awsRegion userIdentity.principalId 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
|`aws_detect_users_creating_keys_with_encrypt_policy_without_mfa_filter`

Macros

The SPL above uses the following Macros:

:information_source: aws_detect_users_creating_keys_with_encrypt_policy_without_mfa_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • eventName
  • eventSource
  • eventID
  • awsRegion
  • requestParameters.policy
  • userIdentity.principalId

How To Implement

You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 AWS account is potentially compromised and user $userIdentity.principalId$ is trying to compromise other accounts.

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

Reference

Test Dataset

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 | version: 1