Mapping Data Sources
Inputs:
- Detection objective and hypothesis from previous skill
- Available data sources in target environment
- Logging configuration details (if known)
Workflow steps:
Identify required data sources - List all log sources needed to observe the malicious behavior:
- EDR/XDR telemetry (process, file, network, registry)
- OS native logs (Windows Event Logs, Syslog, auditd)
- Cloud audit logs (Azure AD, AWS CloudTrail, GCP)
- SaaS application logs (Okta, O365, GSuite)
- Network telemetry (firewall, DNS, proxy, NetFlow)
Prioritize data sources - Rank by:
- Critical: Required for core detection logic
- High: Significantly improves detection accuracy
- Medium: Provides enrichment context
- Low: Nice-to-have for investigation
Map to specific fields - For each critical data source, document exact fields needed:
- Field name (as it appears in logs)
- Expected values or patterns
- Field availability (always present vs. conditional)
- Example values
Document visibility gaps - Identify missing telemetry:
- Data sources not available in environment
- Required fields not logged by default
- Configuration changes needed (e.g., "Requires Sysmon Event ID 10 with LSASS access auditing")
- Vendor-specific limitations
Define data quality requirements - Specify:
- Required log retention period
- Acceptable data latency (real-time vs. delayed ingestion)
- Completeness requirements (must capture 100% vs. sampling acceptable)
- Field parsing dependencies
Create data availability matrix - Table format:
| Data Source | Priority | Required Fields | Availability | Gaps/Requirements |
Outputs: Structured telemetry mapping document containing:
- Prioritized data source list
- Field-level mapping table
- Visibility gap analysis
- Configuration requirements
- Data quality specifications
- Alternative data sources (if primary unavailable)
References:
- Common Information Model (CIM) schemas
- Elastic Common Schema (ECS)
- OSSEM (Open Source Security Events Metadata)