Detection rules › Splunk
AWS SetDefaultPolicyVersion
The following analytic detects when a user sets a default policy version in AWS. It leverages AWS CloudTrail logs to identify the SetDefaultPolicyVersion event from the IAM service. This activity is significant because attackers may exploit this technique for privilege escalation, especially if previous policy versions grant more extensive permissions than the current one. If confirmed malicious, this could allow an attacker to gain elevated access to AWS resources, potentially leading to unauthorized actions and data breaches.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1078.004 Valid Accounts: Cloud Accounts |
| Persistence | T1078.004 Valid Accounts: Cloud Accounts |
| Privilege Escalation | T1078.004 Valid Accounts: Cloud Accounts |
| Stealth | T1078.004 Valid Accounts: Cloud Accounts |
Event coverage
| Provider | Event |
|---|---|
| AWS-iam | SetDefaultPolicyVersion |
Rules detecting the same action
Other rules on this platform that filter on the same API call or operation.
Rule body splunk
name: AWS SetDefaultPolicyVersion
id: 2a9b80d3-6340-4345-11ad-212bf3d0dac4
version: 11
creation_date: '2021-03-02'
modification_date: '2026-05-13'
author: Bhavin Patel, Splunk
status: production
type: TTP
description: The following analytic detects when a user sets a default policy version in AWS. It leverages AWS CloudTrail logs to identify the `SetDefaultPolicyVersion` event from the IAM service. This activity is significant because attackers may exploit this technique for privilege escalation, especially if previous policy versions grant more extensive permissions than the current one. If confirmed malicious, this could allow an attacker to gain elevated access to AWS resources, potentially leading to unauthorized actions and data breaches.
data_source:
- AWS CloudTrail SetDefaultPolicyVersion
search: |-
`cloudtrail` eventName=SetDefaultPolicyVersion eventSource = iam.amazonaws.com
| rename user_name as user
| stats count min(_time) as firstTime max(_time) as lastTime
BY signature dest user
user_agent src vendor_account
vendor_region vendor_product
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `aws_setdefaultpolicyversion_filter`
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: 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
references:
- https://bishopfox.com/blog/privilege-escalation-in-aws
- https://rhinosecuritylabs.com/aws/aws-privilege-escalation-methods-mitigation-part-2/
drilldown_searches:
- name: View the detection results for - "$user$"
search: '%original_detection_search% | search user = "$user$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$user$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
finding:
title: From IP address $src$, user $user$ has trigged an action $signature$ for updating the the default policy version
entity:
field: user
type: user
score: 50
threat_objects:
- field: src
type: ip_address
analytic_story:
- AWS IAM Privilege Escalation
asset_type: AWS Account
mitre_attack_id:
- T1078.004
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: cloud
security_domain: threat
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1078/aws_setdefaultpolicyversion/aws_cloudtrail_events.json
sourcetype: aws:cloudtrail
source: aws_cloudtrail
test_type: unit
Stages and Predicates
Stage 1: search
`cloudtrail` eventName=SetDefaultPolicyVersion eventSource = iam.amazonaws.com
Stage 2: rename
| rename user_name as user
Stage 3: stats
| stats count min(_time) as firstTime max(_time) as lastTime
BY signature dest user
user_agent src vendor_account
vendor_region vendor_product
Stage 4: search
| `security_content_ctime(firstTime)`
Stage 5: search
| `security_content_ctime(lastTime)`
Stage 6: search
| `aws_setdefaultpolicyversion_filter`
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
eventName | eq |
|
eventSource | eq |
|
sourcetype | eq |
|