The following analytic identifies the use of the Windows Disk Image Utility,
dism.exe, to remove Windows Defender. Adversaries may use
dism.exe to disable Defender before completing their objective.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint- Datasource: Splunk Add-on for Sysmon
- Last Updated: 2021-11-17
- Author: Michael Haag, Splunk
- ID: 8567da9e-47f0-11ec-99a9-acde48001122
Kill Chain Phase
1 2 3 4 5 6 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=dism.exe (Processes.process="*/online*" AND Processes.process="*/disable-feature*" AND Processes.process="*Windows-Defender*" AND Processes.process="*/remove*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_dism_remove_defender_filter`
The SPL above uses the following Macros:
windows_dism_remove_defender_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
How To Implement
To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the
Endpoint datamodel in the
Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.
Known False Positives
Some legitimate administrative tools leverage
dism.exe to manipulate packages and features of the operating system. Filter as needed.
Associated Analytic story
|80.0||80||100||An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to disable Windows Defender.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1