Detection: Suspicious msbuild path

Description

The following analytic detects the execution of msbuild.exe from a non-standard path. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that deviate from typical msbuild.exe locations. This activity is significant because msbuild.exe is commonly abused by attackers to execute malicious code, and running it from an unusual path can indicate an attempt to evade detection. If confirmed malicious, this behavior could allow an attacker to execute arbitrary code, potentially leading to system compromise and further malicious activities.

Search

1
2| tstats `security_content_summariesonly` count values(Processes.process_name) as process_name values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_msbuild` AND (Processes.process_path!=*\\framework*\\v*\\*) by Processes.dest Processes.original_file_name Processes.parent_process Processes.user 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)`
6| `suspicious_msbuild_path_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

Some legitimate applications may use a moved copy of msbuild.exe, triggering a false positive. Baselining of MSBuild.exe usage is recommended to better understand it's path usage. Visual Studio runs an instance out of a path that will need to be filtered on.

Associated Analytic Story

• BlackByte Ransomware

• Cobalt Strike

• Graceful Wipe Out Attack

• Living Off The Land

• Masquerading - Rename System Utilities

• Trusted Developer Utilities Proxy Execution MSBuild

Risk Based Analytics (RBA)

References

• https://lolbas-project.github.io/lolbas/Binaries/Msbuild/

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1127.001/T1127.001.md

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: 5