splunk-security_content/docs/_posts/2021-03-02-aws_setdefaultpolicyversion.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
AWS SetDefaultPolicyVersion	Cloud Accounts, Valid Accounts	Cloud	2021-03-02	true		TTP T1078.004 Cloud Accounts Defense Evasion Persistence Privilege Escalation Initial Access T1078 Valid Accounts Defense Evasion Persistence Privilege Escalation Initial Access Splunk Security Analytics for AWS Splunk Enterprise Splunk Enterprise Security Splunk Cloud Actions on Objectives

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Description

This search looks for AWS CloudTrail events where a user has set a default policy versions. Attackers have been know to use this technique for Privilege Escalation in case the previous versions of the policy had permissions to access more resources than the current version of the policy

• Type: TTP
• Product: Splunk Security Analytics for AWS, Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel:
• Last Updated: 2021-03-02
• Author: Bhavin Patel, Splunk
• ID: 2a9b80d3-6340-4345-11ad-212bf3d0dac4

ATT&CK

ID	Technique	Tactic
T1078.004	Cloud Accounts	Defense Evasion, Persistence, Privilege Escalation, Initial Access
T1078	Valid Accounts	Defense Evasion, Persistence, Privilege Escalation, Initial Access

Search

`cloudtrail` eventName=SetDefaultPolicyVersion eventSource = iam.amazonaws.com 
| stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.policyArn) as policy_arn by src requestParameters.versionId eventName eventSource aws_account_id errorCode userAgent eventID awsRegion userIdentity.principalId user_arn 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `aws_setdefaultpolicyversion_filter`

Associated Analytic Story

• AWS IAM Privilege Escalation

How To Implement

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

Required field

• _time
• eventName
• userAgent
• errorCode
• requestParameters.userName
• eventSource

Kill Chain Phase

• Actions on Objectives

Known False Positives

While this search has no known false positives, it is possible that an AWS admin has legitimately set a default policy to allow a user to access all resources. That said, AWS strongly advises against granting full control to all AWS resources

RBA

Risk Score	Impact	Confidence	Message
30.0	50	60	From IP address sourceIPAddress, user agent userAgent has trigged an event eventName for updating the the default policy version

Reference

• https://labs.bishopfox.com/tech-blog/privilege-escalation-in-aws
• https://rhinosecuritylabs.com/aws/aws-privilege-escalation-methods-mitigation-part-2/

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1078/aws_setdefaultpolicyversion/aws_cloudtrail_events.json

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