Analyze Syslog Ingestion Delays in Microsoft Sentinel with KQL

Checking ingestion delays in Syslog data is critical for timely detection and alerting in cybersecurity systems. This technique uses KQL to analyze the time gap between the event generation and its ingestion into Microsoft Sentinel by key identifiers such as ProcessName, SourceSystem, and HostName. Monitoring these delays helps ensure alerts triggered by Azure Sentinel are accurate and data latency is minimized.

Risk

Ingestion delays can cause late or missed alerts in security monitoring systems. Since Azure Sentinel scheduled alert rules have a built-in 5-minute delay, any additional ingestion lag could impact threat detection timing. If ingestion latency exceeds expected thresholds, critical security events might be overlooked or reported too late for effective response.

Query

Microsoft Sentinel

Syslog
| extend IngestionTime = ingestion_time()
| extend Delay = ingestion_time() - TimeGenerated
| summarize max(Delay) by ProcessName, SourceSystem, HostName

This query calculates the delay by subtracting the original event timestamp (TimeGenerated) from the ingestion time, then summarizes the maximum delay for each ProcessName, SourceSystem, and HostName grouping. It helps quickly identify sources with the highest ingestion latency.

References

• Handle ingestion delay in Microsoft Sentinel | Microsoft Learn
• Handling ingestion delay in Azure Sentinel scheduled alert rules – Microsoft Community Hub