In-Memory MSBuild Proxy Execution of a Project From a User-Writable Path (via process_creation)

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1127.001MSBuild
Persistence
Priv Esc
Defense Evasion
- T1127.001MSBuild
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects MSBuild.exe building an inline-task project file located in a user, temp or AppData directory, a pattern adversaries use to compile and run C# payloads in memory under a signed Microsoft developer utility. MSBuild proxy execution is a trusted-developer-utility abuse technique in the Red Canary Threat Detection Report. Detecting builds sourced from user-writable paths surfaces code execution that evades application allowlisting.

Reporting behind it

Related detections9 linkedT1127.001 — drag to rearrange

Malicious MSBuild Execution of Downloaded csproj Project File (via process_creation)

Suspicious MSBuild Inline Task Compilation of mini.xml

Suspicious MSBuild Execution Spawned by Command Shell for Process Hollowing (via process_creation)

Suspicious MSBuild Execution of Inline Payload (via process_creation)

Suspicious MSBuild Execution as LOLBin from User-Writable Path (via process_creation)

Suspicious Local XML Compilation via MSBuild

Malicious Winlogon Shell Hijack Loading MSBuild

Proxy Execution via MSBuild Running Inline Task XML

MSBuild Executing Non-Project File or Remote Payload

In-Memory MSBuild Proxy Execution of a Project From a User-Writable Path (via process_creation)

Pivot detection · T1127.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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