This search looks for high frequency of file deletion relative to process name and process id. These events usually happen when the ransomware tries to encrypt the files with the ransomware file extensions and sysmon treat the original files to be deleted as soon it was replace as encrypted data.
- Type: Anomaly
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-03-16
- Author: Teoderick Contreras
- ID: 45b125c4-866f-11eb-a95a-acde48001122
`sysmon` EventCode=23 TargetFilename IN ("*\.cmd", "*\.ini","*\.gif", "*\.jpg", "*\.jpeg", "*\.db", "*\.ps1", "*\.doc*", "*\.xls*", "*\.ppt*", "*\.bmp","*\.zip", "*\.rar", "*\.7z", "*\.chm", "*\.png", "*\.log", "*\.vbs", "*\.js") | stats values(TargetFilename) as deleted_files min(_time) as firstTime max(_time) as lastTime count by Computer user EventCode Image ProcessID |where count >=100 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `high_file_deletion_frequency_filter`
Associated Analytic Story
How To Implement
To successfully implement this search, you need to be ingesting logs with the deleted target file name, process name and process id from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
Kill Chain Phase
Known False Positives
user may delete bunch of pictures or files in a folder.
|72.0||90||80||High frequency file deletion activity detected on host $Computer$|
source | version: 1