Malicious aspnet_compiler.exe Injection Host Spawned by PowerShell via process_creation

ATT&CK techniques

Priv Esc → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1055Process Injection
Defense Evasion
- T1055Process Injection
- T1218System Binary Proxy Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the .NET build utility aspnet_compiler.exe being launched by PowerShell, the process-injection host abused by the multi-stage Phantom Stealer campaign to run reflectively loaded payload code. Spawning the signed compiler from a scripting engine is a wrong-context indicator that the stealer is hollowing a trusted binary to evade detection, exposing the injection before credential theft and SMTP exfiltration.

Reporting behind it

Related detections9 linkedT1055 — drag to rearrange

Suspicious RegAsm or RegSvcs Spawned by Script Host (via process_creation)

Windows Image Load: coregen.exe Potential DLL Sideloading

Windows: Files created by Microsoft Sync Center (mobsync.exe) with .dll/.exe extensions

Windows Microsoft Sync Center (mobsync.exe) Network Connections to Public IPs

Suspicious AppLaunch.exe Spawned As Injection Target (via process_creation)

Suspicious BugSleep Marker File in Public Directory

Suspicious Cabinet Extraction of Masqueraded vstm Archive via extrac32

Suspicious CRAT Injection Named Pipe ChromeUpdatePipe (via pipe_created)

Malicious DLL Execution via Wuauclt Update Handler (via process_creation)

Malicious aspnet_compiler.exe Injection Host Spawned by PowerShell via process_creation

Pivot detection · T1055 · 9 related

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

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →