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[REVIEW] log-analysis: add timestamp normalization and clock-skew evidence gates #1422

@MAUROCERON

Description

@MAUROCERON

Gap

The log-analysis skill already asks analysts to define a time window and then correlate events into a timeline, but it does not require an explicit timestamp trust check before cross-source correlation. In real investigations, Windows/Sysmon, Linux syslog, cloud audit logs, and SIEM-normalized events can disagree because of local time zones, missing year/timezone fields, parser choices, ingestion lag, queue backlog, or host clock skew.

Expected improvement

Add a timestamp normalization and clock-skew evidence gate before timeline reconstruction. The gate should require analysts to document event time, ingestion/index time, parser timestamp field, source time zone, clock synchronization / skew evidence, and a confidence decision. If these cannot be established, the timeline should be marked Not Evaluable or scoped to lower-confidence findings rather than presented as definitive.

Validation fixture

Add edge cases covering Windows local time ambiguity, CloudTrail eventTime vs SIEM ingestion delay, Sysmon host clock skew, Linux auth logs with missing year/timezone, parser mapping mistakes, and a complete normalized multi-source timeline.

References

  • NIST SP 800-92 describes clock synchronization issues and how inaccurate host clocks make multi-host log analysis harder.
  • AWS CloudTrail documents eventTime and notes that CloudTrail events do not appear in a guaranteed order.
  • Splunk documents _time as event time and _indextime as index time.
  • Elastic documents ingest lag as event.ingested - @timestamp and warns that @timestamp semantics vary by source.

Payment details can be provided privately after maintainer acceptance.

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