TTP Detection Rule: Suspicious network connection from MSBuild

Query Information

MITRE ATT&CK Technique(s)

Technique ID	Title	Link
T1127.001	Trusted Developer Utilities Proxy Execution: MSBuild	MSBuild

Description

Detection opportunity: MSBuild without commands

In some detections, we observed the Microsoft Build Engine (msbuild.exe) making outbound network connections to IPs associated with the ArechClient2 remote access tool. In general, it is suspicious for msbuild.exe to execute without a corresponding command line, which is precisely what we observed here. Simply looking for execution of msbuild.exe without a corresponding command line and examining surrounding activity for suspicious network connections and child processes could help detect this threat.

Risk

FIN7, ZLoader, and FakeBat have been observed performing this behaviour in recent intrusions. Adversaries may modify and/or disable security tools to avoid possible detection of their malware/tools and activities.

Author

• Name: Gavin Knapp
• Github: https://github.com/m4nbat
• Twitter: https://twitter.com/knappresearchlb
• LinkedIn: https://www.linkedin.com/in/grjk83/
• Website:

References

• MSIX installer malware delivery on the rise across multiple campaigns

Defender XDR

// Detection opportunity 5: MSBuild without commands
DeviceNetworkEvents
| where InitiatingProcessFileName =~ "msbuild.exe" and (isempty(InitiatingProcessCommandLine) or InitiatingProcessCommandLine =~ "msbuild.exe")

Sentinel

// Detection opportunity 5: MSBuild without commands
DeviceNetworkEvents
| where InitiatingProcessFileName =~ "msbuild.exe" and (isempty(InitiatingProcessCommandLine) or InitiatingProcessCommandLine =~ "msbuild.exe")