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Anthropic-Cybersecurity-Skills/skills/analyzing-cloud-storage-access-patterns/SKILL.md
T
Mahipal 2fb6a9faff Rewrite 548 skill descriptions to the activation rubric
Each rewritten description now states both what the skill does (concrete
capability, named tools/artifacts) and an explicit when-to-use trigger,
improving agent discovery/activation. Grounded in each skill's own body;
changes confined to the `description` field only (bodies and all other
frontmatter untouched). Produced by a gated audit->rewrite->recheck loop
(548 -> 0 flagged) with a sampled anti-invention check (0 ungrounded).

Schema: 817/817 pass. Framework-ID gate: 0 defects.
2026-08-02 09:32:13 -07:00

2.3 KiB

name, description, domain, subdomain, tags, version, author, license, atlas_techniques, nist_ai_rmf, nist_csf, mitre_attack
name description domain subdomain tags version author license atlas_techniques nist_ai_rmf nist_csf mitre_attack
analyzing-cloud-storage-access-patterns 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. cybersecurity cloud-security
cloud-security
aws-s3
gcs
azure-blob-storage
cloudtrail
data-access-anomaly
exfiltration-detection
1.0 mahipal Apache-2.0
AML.T0024
AML.T0056
MEASURE-2.7
MAP-5.1
MANAGE-2.4
PR.IR-01
ID.AM-08
GV.SC-06
DE.CM-01
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"}}