name: analyzing-cloud-storage-access-patterns description: Detect abnormal access in AWS S3, GCS, and Azure Blob Storage by analyzing CloudTrail Data Events, GCS audit logs, and Azure Storage Analytics for after-hours bulk downloads, new-IP access, and API-call spikes (e.g. GetObject) via statistical baselines and time-series anomaly detection. Use when investigating suspected cloud data exfiltration or building related detection rules. domain: cybersecurity subdomain: cloud-security tags:

• cloud-security
• aws-s3
• gcs
• azure-blob-storage
• cloudtrail
• data-access-anomaly
• exfiltration-detection version: '1.0' author: mahipal license: Apache-2.0 atlas_techniques:
• AML.T0024
• AML.T0056 nist_ai_rmf:
• MEASURE-2.7
• MAP-5.1
• MANAGE-2.4 nist_csf:
• PR.IR-01
• ID.AM-08
• GV.SC-06
• DE.CM-01 mitre_attack:
• T1530
• T1567.002
• T1619
• T1078.004
• T1048

Analyzing Cloud Storage Access Patterns

When to Use

• When investigating security incidents that require analyzing cloud storage access patterns
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Familiarity with cloud security concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Instructions

1. Install dependencies: pip install boto3 requests
2. Query CloudTrail for S3 Data Events using AWS CLI or boto3.
3. Build access baselines: hourly request volume, per-user object counts, source IP history.
4. Detect anomalies:
   • After-hours access (outside 8am-6pm local time)
   • Bulk downloads: >100 GetObject calls from single principal in 1 hour
   • New source IPs not seen in the prior 30 days
   • ListBucket enumeration spikes (reconnaissance indicator)
5. Generate prioritized findings report.

python scripts/agent.py --bucket my-sensitive-data --hours-back 24 --output s3_access_report.json

Examples

CloudTrail S3 Data Event

{"eventName": "GetObject", "requestParameters": {"bucketName": "sensitive-data", "key": "financials/q4.xlsx"},
 "sourceIPAddress": "203.0.113.50", "userIdentity": {"arn": "arn:aws:iam::123456789012:user/analyst"}}