Sigma rule: AWS IAM S3Browser Templated S3 Bucket Policy Creation

Rule

Title

AWS IAM S3Browser Templated S3 Bucket Policy Creation

Status

test

Level

high

Author

[email protected] (@danielhbohannon)

Date

2023-05-17

File

rules/cloud/aws/cloudtrail/aws_iam_s3browser_templated_s3_bucket_policy_creation.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects S3 browser utility creating Inline IAM policy containing default S3 bucket name placeholder value of "<YOUR-BUCKET-NAME>".

Log source

product

aws

service

cloudtrail

Detection

selection:
    eventSource: iam.amazonaws.com
    eventName: PutUserPolicy
    userAgent|contains: 'S3 Browser'
    requestParameters|contains|all:
        - '"arn:aws:s3:::<YOUR-BUCKET-NAME>/*"'
        - '"s3:GetObject"'
        - '"Allow"'
condition: selection

False positives (as the rule lists them)

• Valid usage of S3 browser with accidental creation of default Inline IAM policy without changing default S3 bucket name placeholder value

Tags

• attack.execution
• attack.stealth
• attack.t1059.009
• attack.persistence
• attack.initial-access
• attack.privilege-escalation
• attack.t1078.004

MITRE ATT&CK ids this rule names

• T1059.009
• T1078.004

References

• https://permiso.io/blog/s/unmasking-guivil-new-cloud-threat-actor

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/cloud/aws/cloudtrail/aws_iam_s3browser_templated_s3_bucket_policy_creation.yml