Detection rules › Sigma
Potentially Suspicious ASP.NET Compilation Via AspNetCompiler
Detects execution of "aspnet_compiler.exe" with potentially suspicious paths for compilation.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1127 Trusted Developer Utilities Proxy Execution |
| Stealth | T1127 Trusted Developer Utilities Proxy Execution |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
title: Potentially Suspicious ASP.NET Compilation Via AspNetCompiler
id: 9f50fe98-fe5c-4a2d-86c7-fad7f63ed622 # Susp Paths
related:
- id: 9ccba514-7cb6-4c5c-b377-700758f2f120 # SuspChild
type: similar
- id: 4c7f49ee-2638-43bb-b85b-ce676c30b260 # TMP File
type: similar
- id: a01b8329-5953-4f73-ae2d-aa01e1f35f00 # Exec
type: similar
status: test
description: Detects execution of "aspnet_compiler.exe" with potentially suspicious paths for compilation.
references:
- https://lolbas-project.github.io/lolbas/Binaries/Aspnet_Compiler/
- https://ijustwannared.team/2020/08/01/the-curious-case-of-aspnet_compiler-exe/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-08-14
modified: 2025-02-24
tags:
- attack.execution
- attack.stealth
- attack.t1127
logsource:
category: process_creation
product: windows
detection:
selection:
Image|contains:
- ':\Windows\Microsoft.NET\Framework\'
- ':\Windows\Microsoft.NET\Framework64\'
- ':\Windows\Microsoft.NET\FrameworkArm\'
- ':\Windows\Microsoft.NET\FrameworkArm64\'
Image|endswith: '\aspnet_compiler.exe'
CommandLine|contains:
# Note: add other potential suspicious paths
- '\Users\Public\'
- '\AppData\Local\Temp\'
- '\AppData\Local\Roaming\'
- ':\Temp\'
- ':\Windows\Temp\'
- ':\Windows\System32\Tasks\'
- ':\Windows\Tasks\'
condition: selection
falsepositives:
- Unknown
level: high
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
Image|contains:
- ':\Windows\Microsoft.NET\Framework\'
- ':\Windows\Microsoft.NET\Framework64\'
- ':\Windows\Microsoft.NET\FrameworkArm\'
- ':\Windows\Microsoft.NET\FrameworkArm64\'
Image|endswith: '\aspnet_compiler.exe'
CommandLine|contains:
- '\Users\Public\'
- '\AppData\Local\Temp\'
- '\AppData\Local\Roaming\'
- ':\Temp\'
- ':\Windows\Temp\'
- ':\Windows\System32\Tasks\'
- ':\Windows\Tasks\'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|
Image | match |
|