KQL Search

let interval=24h;
EmailAttachmentInfo
| where isnotempty(FileType)
| where FileType !contains "png"
| where FileType !contains "jpeg"
| where FileType !contains "gif"
| where FileType !contains "html"
| make-series FileTypeCount = count() default=0 on Timestamp from ago(7d) to now() step interval by FileType
| extend (flag, score, baseline) = series_decompose_anomalies(FileTypeCount)
| mv-expand with_itemindex = FlagIndex flag to typeof(int) // Expand, but this time include the index in the array as FlagIndex
| where flag == 1  // Once again, filter only to spikes
| extend SpikeScore = todouble(score[FlagIndex]) // This will get the specific score associated with the detected spike
| summarize MaxScore = max(SpikeScore) by FileType
| top 5 by MaxScore desc
| join kind=rightsemi EmailAttachmentInfo on FileType // Rejoin top 5 anomalous FileTypes to all their attachment instances
| make-series FileTypeCount = count() default=0 on Timestamp from ago(7d) to now() step interval by FileType
| mv-expand FileTypeCount, Timestamp
| project  FileType, todatetime(Timestamp), toint(FileTypeCount)
| render timechart