Suspicious C# IL Code Compilation Through Ilasm.EXE (via process_creation)

title: Suspicious C# IL Code Compilation Through Ilasm.EXE (via process_creation)
id: 19d70846-7a7f-5641-b8fb-502e55a80a59
status: stable
description: This rule detects the use of "Ilasm.EXE" to compile C# intermediate (IL) code to EXE or DLL.
references:
    - https://attack.mitre.org/techniques/T1127/
    - https://lolbas-project.github.io/lolbas/Binaries/Ilasm/
    - https://www.echotrail.io/insights/search/ilasm.exe
author: Huntrule Team
date: 2026-07-10
tags:
    - attack.execution
    - attack.stealth
    - attack.t1127
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\ilasm.exe'
        - OriginalFileName: 'ilasm.exe'
    selection_cli:
        CommandLine|contains:
            - ' /dll'
            - ' /exe'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium