Ilasm.exe

used for compile c# code into dll or exe.

Paths

• C:\Windows\Microsoft.NET\Framework\v4.0.30319\ilasm.exe
• C:\Windows\Microsoft.NET\Framework64\v4.0.30319\ilasm.exe

Commands

Compile

Binary file used by .NET to compile C#/intermediate (IL) code to .exe

Use case: Compile attacker code on system. Bypass defensive counter measures.

Privileges: User

ilasm.exe {PATH_ABSOLUTE:.txt} /exe

Compile

Binary file used by .NET to compile C#/intermediate (IL) code to dll

Use case: A description of the usecase

Privileges: User

ilasm.exe {PATH_ABSOLUTE:.txt} /dll

Detection

• IOC: Ilasm may not be used often in production environments (such as on endpoints)
• Sigma: https://github.com/SigmaHQ/sigma/blob/bea6f18d350d9c9fdc067f93dde0e9b11cc22dc2/rules/windows/process_creation/proc_creation_win_lolbin_ilasm.yml

Resources

• https://github.com/LuxNoBulIshit/BeforeCompileBy-ilasm/blob/master/hello_world.txt