An IS auditor has been asked to review an event log aggregation system to ensure risk management practices have been applied. Which of the following should be of MOST concern to the auditor?

If completeness testing has not been performed on the log data, there is no assurance that all relevant log entries are being captured, transmitted, and stored by the aggregation system. This lack of completeness means critical security events or indicators of compromise could be missing, severely undermining the system's utility for risk management and incident response.

While real-time log ingestion is often preferred, uploading log feeds via batch process is not inherently a 'most concerning' risk, as long as the batch frequency meets operational and security requirements.

Log data not being normalized can make analysis more difficult, but it doesn't fundamentally compromise the presence of the data itself, which is what completeness ensures.

While data encryption standards are important for protecting log data in transit and at rest, the absence of completeness testing represents a more fundamental flaw, as the data itself might not even be there to protect.