AspNetCompiler Execution

calendar Aug 14, 2023 · attack.defense_evasion attack.t1127  ·
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Detects execution of "aspnet_compiler.exe" which can be abused to compile and execute C# code.

Sigma rule (View on GitHub)

 1title: AspNetCompiler Execution
 2id: a01b8329-5953-4f73-ae2d-aa01e1f35f00 # Exec
 3related:
 4    - id: 9ccba514-7cb6-4c5c-b377-700758f2f120 # SuspChild
 5      type: similar
 6    - id: 4c7f49ee-2638-43bb-b85b-ce676c30b260 # TMP File
 7      type: similar
 8    - id: 9f50fe98-fe5c-4a2d-86c7-fad7f63ed622 # Susp Paths
 9      type: similar
10status: test
11description: Detects execution of "aspnet_compiler.exe" which can be abused to compile and execute C# code.
12references:
13    - https://lolbas-project.github.io/lolbas/Binaries/Aspnet_Compiler/
14    - https://ijustwannared.team/2020/08/01/the-curious-case-of-aspnet_compiler-exe/
15author: frack113
16date: 2021/11/24
17modified: 2023/08/14
18tags:
19    - attack.defense_evasion
20    - attack.t1127
21logsource:
22    category: process_creation
23    product: windows
24detection:
25    selection:
26        Image|contains:
27            - 'C:\Windows\Microsoft.NET\Framework\'
28            - 'C:\Windows\Microsoft.NET\Framework64\'
29        Image|endswith: '\aspnet_compiler.exe'
30    condition: selection
31falsepositives:
32    - Unknown
33level: medium

References

  • Aspnet_compiler | LOLBAS

    Execute C# code with the Build Provider and proper folder structure in place. C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_compiler.exe -v none -p C:\users\cpl.internal\desktop\asptest\ -...


    Read More

  • The Curious Case of Aspnet_Compiler.exe

    Hey all, This post will explore code execution with aspnet_compiler.exe. I’m going to outline how to use the Microsoft signed executable to load & execute a local DLL builder and quickly …


    Read More

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