This analytic is to detect a suspicious child process of MSBuild spawned by Windows Script Host - cscript or wscript. This behavior or event are commonly seen and used by malware or adversaries to execute malicious msbuild process using malicious script in the compromised host. During triage, review parallel processes and identify any file modifications. MSBuild may load a script from the same path without having command-line arguments.
- Type: TTP
Product: Splunk Behavioral Analytics
- Last Updated: 2022-03-03
- Author: Michael Haag, Splunk
- ID: 92886f1c-9b11-11ec-848a-acde48001122
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 $main = from source | eval timestamp = time | eval metadata_uid = metadata.uid | eval process_pid = process.pid | eval process_file = process.file | eval process_file_path = process_file.path | eval process_file_name = lower(process_file.name) | eval process_cmd_line = process.cmd_line | eval actor_user = actor.user | eval actor_user_name = actor_user.name | eval actor_process = actor.process | eval actor_process_pid = actor_process.pid | eval actor_process_file = actor_process.file | eval actor_process_file_path = actor_process_file.path | eval actor_process_file_name = actor_process_file.name | eval device_hostname = device.hostname | where process_file_name="msbuild.exe" AND (match(actor_process_file_name, /(?i)cscript.exe/)=true OR match(actor_process_file_name, /(?i)wscript.exe/)=true) --finding_report--
The SPL above uses the following Macros:
windows_script_host_spawn_msbuild_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
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
False positives should be limited as developers do not spawn MSBuild via a WSH.
Associated Analytic Story
|80.0||80||100||An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest_device_id$ by user $dest_user_id$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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