Detection: WBAdmin Delete System Backups

Description

The following analytic detects the execution of wbadmin.exe with flags that delete backup files, specifically targeting catalog or system state backups. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line arguments. This activity is significant because it is commonly used by ransomware to prevent recovery by deleting system backups. If confirmed malicious, this action could severely hinder recovery efforts, leading to prolonged downtime and potential data loss.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_wbadmin` AND Processes.process="*delete*" AND (Processes.process="*catalog*" OR Processes.process="*backup*") by Processes.process_name Processes.process Processes.parent_process_name Processes.dest Processes.user 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)`
6| `wbadmin_delete_system_backups_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Administrators may modify the boot configuration.

Associated Analytic Story

• Chaos Ransomware

• Prestige Ransomware

• Ransomware

• Ryuk Ransomware

Risk Based Analytics (RBA)

References

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1490/T1490.md

• https://thedfirreport.com/2020/10/08/ryuks-return/

• https://attack.mitre.org/techniques/T1490/

• https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/wbadmin

• https://www.welivesecurity.com/2019/04/30/buhtrap-backdoor-ransomware-advertising-platform/

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4