Anthropic-Cybersecurity-Skills/skills/analyzing-cloud-storage-access-patterns/SKILL.md

name, description, domain, subdomain, tags, version, author, license

name	description	domain	subdomain	tags	version	author	license
analyzing-cloud-storage-access-patterns	Detect abnormal access patterns in AWS S3, GCS, and Azure Blob Storage by analyzing CloudTrail Data Events, GCS audit logs, and Azure Storage Analytics. Identifies after-hours bulk downloads, access from new IP addresses, unusual API calls (GetObject spikes), and potential data exfiltration using statistical baselines and time-series anomaly detection.	cybersecurity	cloud-security	analyzing cloud storage access	1.0	mahipal	MIT

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"}}