Suspicious Child Process of aspnet_compiler.exe on Windows
Alerts when aspnet_compiler.exe spawns calc/notepad or executes from public/temp/Task-related paths on Windows.
- Product
- windows
- Category
- process_creation
- Author
- Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
- Published
- 2023-08-14
- Updated
- 2026-07-31
ATT&CK techniques
Execution → Defense EvasionRecon
Resource Dev
Initial Access
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags process creation events where a child process is spawned by aspnet_compiler.exe and the child image or path matches suspicious patterns. Attackers may abuse aspnet_compiler.exe to launch additional tooling for execution and stealth, so correlating parent-child relationships can reveal unexpected activity. It relies on Windows process creation telemetry capturing ParentImage and the child Image (including executable name and common writable or task-related paths).
Reporting behind it
- lolbas-project.github.iohttps://lolbas-project.github.io/lolbas/Binaries/Aspnet_Compiler/
- ijustwannared.teamhttps://ijustwannared.team/2020/08/01/the-curious-case-of-aspnet_compiler-exe/
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_aspnet_compiler_susp_child_process.yml
Changelog
v2- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: Suspicious Child Process of aspnet_compiler.exe on Windows
id: de301eb0-ce44-4ef0-ade2-e0feb31953c9
related:
- id: 4c7f49ee-2638-43bb-b85b-ce676c30b260
type: similar
- id: 9f50fe98-fe5c-4a2d-86c7-fad7f63ed622
type: similar
- id: a01b8329-5953-4f73-ae2d-aa01e1f35f00
type: similar
- id: 9ccba514-7cb6-4c5c-b377-700758f2f120
type: derived
status: test
description: This rule flags process creation events where a child process is spawned by aspnet_compiler.exe and the child image or path matches suspicious patterns. Attackers may abuse aspnet_compiler.exe to launch additional tooling for execution and stealth, so correlating parent-child relationships can reveal unexpected activity. It relies on Windows process creation telemetry capturing ParentImage and the child Image (including executable name and common writable or task-related paths).
references:
- https://lolbas-project.github.io/lolbas/Binaries/Aspnet_Compiler/
- https://ijustwannared.team/2020/08/01/the-curious-case-of-aspnet_compiler-exe/
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_aspnet_compiler_susp_child_process.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-08-14
tags:
- attack.execution
- attack.stealth
- attack.t1127
logsource:
category: process_creation
product: windows
detection:
selection_parent:
ParentImage|endswith: \aspnet_compiler.exe
selection_child:
- Image|endswith:
- \calc.exe
- \notepad.exe
- Image|contains:
- \Users\Public\
- \AppData\Local\Temp\
- \AppData\Local\Roaming\
- :\Temp\
- :\Windows\Temp\
- :\Windows\System32\Tasks\
- :\Windows\Tasks\
condition: all of selection_*
falsepositives:
- Unknown
level: high
license: DRL-1.1