Detection rules › Splunk
AWS ECR Container Upload Unknown User
The following analytic detects the upload of a new container image to AWS Elastic Container Registry (ECR) by an unknown user. It leverages AWS CloudTrail logs to identify PutImage events from the ECR service, filtering out known users. This activity is significant because container uploads should typically be performed by a limited set of authorized users. If confirmed malicious, this could indicate unauthorized access, potentially leading to the deployment of malicious containers, data exfiltration, or further compromise of the AWS environment.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1204.003 User Execution: Malicious Image |
Event coverage
Rules detecting the same action
Other rules on this platform that filter on the same API call or operation.
- AWS ECR Container Upload Outside Business Hours (Splunk)
- ECR CRUD Actions (Panther)
Rule body splunk
name: AWS ECR Container Upload Unknown User
id: 300688e4-365c-4486-a065-7c884462b31d
version: 12
creation_date: '2021-08-19'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: Anomaly
description: The following analytic detects the upload of a new container image to AWS Elastic Container Registry (ECR) by an unknown user. It leverages AWS CloudTrail logs to identify `PutImage` events from the ECR service, filtering out known users. This activity is significant because container uploads should typically be performed by a limited set of authorized users. If confirmed malicious, this could indicate unauthorized access, potentially leading to the deployment of malicious containers, data exfiltration, or further compromise of the AWS environment.
data_source:
- AWS CloudTrail PutImage
search: |-
`cloudtrail` eventSource=ecr.amazonaws.com eventName=PutImage NOT `aws_ecr_users`
| rename requestParameters.* as *
| rename repositoryName AS image
| rename user_name as user
| stats count min(_time) as firstTime max(_time) as lastTime
BY signature user user_agent
src vendor_account vendor_region
vendor_product image
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `aws_ecr_container_upload_unknown_user_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: No false positives have been identified at this time.
references:
- https://attack.mitre.org/techniques/T1204/003/
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"
intermediate_findings:
entities:
- field: user
type: user
score: 20
message: Container uploaded from unknown user $user$
threat_objects:
- field: src
type: ip_address
analytic_story:
- Dev Sec Ops
asset_type: AWS Account
mitre_attack_id:
- T1204.003
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: cloud
security_domain: network
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1204.003/aws_ecr_container_upload/aws_ecr_container_upload.json
sourcetype: aws:cloudtrail
source: aws_cloudtrail
test_type: unit
Stages and Predicates
Stage 1: search
`cloudtrail` eventSource=ecr.amazonaws.com eventName=PutImage NOT `aws_ecr_users`
Stage 2: rename
| rename requestParameters.* as *
Stage 3: rename
| rename repositoryName AS image
Stage 4: rename
| rename user_name as user
Stage 5: stats
| stats count min(_time) as firstTime max(_time) as lastTime
BY signature user user_agent
src vendor_account vendor_region
vendor_product image
Stage 6: search
| `security_content_ctime(firstTime)`
Stage 7: search
| `security_content_ctime(lastTime)`
Stage 8: search
| `aws_ecr_container_upload_unknown_user_filter`
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
userName | eq | user |
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 |
|