RegAsm.exe

  • File Path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\RegAsm.exe
  • Description: Microsoft .NET Assembly Registration Utility
  • Comments: Flavor=Retail

Hashes

Type Hash
MD5 A4EB36BAE72C5CB7392F2B85609D4A7E
SHA1 5C58053A3A18C0226B98A4AC7E7320581300B6C9
SHA256 DC45704BA97D974D157C1C4A27DBA402AFA595EAC2468D8DEF2EE8D0A2EE9A81
SHA384 D01ADC95EF11EDBFD6B1EA1D926A7030A9782B655C641CACE6D5529287D2396E6226DB90DFD0F30FADD9E303A5962668
SHA512 8EBDD20B7C1EE87AA3766D812960B0D8CFA0A6BA6E371F730E589895D202DD540EB475F69940261C1532E90D1030370E9EB5102CADBF6E546F99B350DE79B95A
SSDEEP 768:/8XcJiMjm2ieHFYPyCsSuJbn8dBhFwjSMF6Iq8KSYDKvc7qWk81:zYMaNyFYPYSAb8dBnWHsPDKvcN91
PESHA1 EC1B45DF76B912BCAB4A524A47D2C3EF82EC98B1
PE256 AC8DAEF33BF5CFD6A93FD30A9100A1F89413C0794F31A91F716A8CB4907BAA0D

Runtime Data

Usage (stdout):

Microsoft .NET Framework Assembly Registration Utility version 4.8.4084.0
for Microsoft .NET Framework version 4.8.4084.0
Copyright (C) Microsoft Corporation.  All rights reserved.

Syntax: RegAsm AssemblyName [Options]
Options:
    /unregister          Unregister types
    /tlb[:FileName]      Export the assembly to the specified type library
                         and register it
    /regfile[:FileName]  Generate a reg file with the specified name
                         instead of registering the types. This option
                         cannot be used with the /u or /tlb options
    /codebase            Set the code base in the registry
    /registered          Only refer to already registered type libraries
    /asmpath:Directory   Look for assembly references here
    /nologo              Prevents RegAsm from displaying logo
    /silent              Silent mode. Prevents displaying of success messages
    /verbose             Displays extra information
    /? or /help          Display this usage message

Usage (stderr):

RegAsm : error RA0000 : Failed to load 'C:\Users\user\help' because it is not a valid .NET assembly

Loaded Modules:

Path
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\RegAsm.exe
C:\Windows\System32\KERNEL32.dll
C:\Windows\System32\KERNELBASE.dll
C:\Windows\SYSTEM32\MSCOREE.DLL
C:\Windows\SYSTEM32\ntdll.dll

Signature

  • Status: Signature verified.
  • Serial: 330000023241FB59996DCC4DFF000000000232
  • Thumbprint: FF82BC38E1DA5E596DF374C53E3617F7EDA36B06
  • Issuer: CN=Microsoft Windows Production PCA 2011, O=Microsoft Corporation, L=Redmond, S=Washington, C=US
  • Subject: CN=Microsoft Windows, O=Microsoft Corporation, L=Redmond, S=Washington, C=US

File Metadata

  • Original Filename: RegAsm.exe
  • Product Name: Microsoft .NET Framework
  • Company Name: Microsoft Corporation
  • File Version: 4.8.4084.0 built by: NET48REL1
  • Product Version: 4.8.4084.0
  • Language: English (United States)
  • Legal Copyright: Microsoft Corporation. All rights reserved.
  • Machine Type: 64-bit

File Scan

  • VirusTotal Detections: 0/75
  • VirusTotal Link: https://www.virustotal.com/gui/file/dc45704ba97d974d157c1c4a27dba402afa595eac2468d8def2ee8d0a2ee9a81/detection

File Similarity (ssdeep match)

File Score
C:\Windows\Microsoft.NET\Framework\v4.0.30319\RegAsm.exe 83

Possible Misuse

The following table contains possible examples of RegAsm.exe being misused. While RegAsm.exe is not inherently malicious, its legitimate functionality can be abused for malicious purposes.

Source Source File Example License
sigma win_possible_applocker_bypass.yml - '\regasm.exe' DRL 1.0
LOLBAS Regasm.yml Name: Regasm.exe  
LOLBAS Regasm.yml - Command: regasm.exe AllTheThingsx64.dll  
LOLBAS Regasm.yml - Command: regasm.exe /U AllTheThingsx64.dll  
LOLBAS Regasm.yml - Path: C:\Windows\Microsoft.NET\Framework\v2.0.50727\regasm.exe  
LOLBAS Regasm.yml - Path: C:\Windows\Microsoft.NET\Framework64\v2.0.50727\regasm.exe  
LOLBAS Regasm.yml - Path: C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe  
LOLBAS Regasm.yml - Path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\regasm.exe  
LOLBAS Regasm.yml - IOC: regasm.exe executing dll file  
LOLBAS Regasm.yml - Link: https://pentestlab.blog/2017/05/19/applocker-bypass-regasm-and-regsvcs/  
LOLBAS Regsvcs.yml Description: Regsvcs and Regasm are Windows command-line utilities that are used to register .NET Component Object Model (COM) assemblies  
LOLBAS Regsvcs.yml - Link: https://pentestlab.blog/2017/05/19/applocker-bypass-regasm-and-regsvcs/  
atomic-red-team index.md - T1218.009 Regsvcs/Regasm MIT License. © 2018 Red Canary
atomic-red-team index.md - Atomic Test #1: Regasm Uninstall Method Call Test [windows] MIT License. © 2018 Red Canary
atomic-red-team windows-index.md - T1218.009 Regsvcs/Regasm MIT License. © 2018 Red Canary
atomic-red-team windows-index.md - Atomic Test #1: Regasm Uninstall Method Call Test [windows] MIT License. © 2018 Red Canary
atomic-red-team matrix.md | | | | | Regsvcs/Regasm | | | | | | | | MIT License. © 2018 Red Canary
atomic-red-team windows-matrix.md | | | | | Regsvcs/Regasm | | | | | | | | MIT License. © 2018 Red Canary
atomic-red-team T1218.009.md # T1218.009 - Regsvcs/Regasm MIT License. © 2018 Red Canary
atomic-red-team T1218.009.md <blockquote>Adversaries may abuse Regsvcs and Regasm to proxy execution of code through a trusted Windows utility. Regsvcs and Regasm are Windows command-line utilities that are used to register .NET Component Object Model (COM) assemblies. Both are digitally signed by Microsoft. (Citation: MSDN Regsvcs) (Citation: MSDN Regasm) MIT License. © 2018 Red Canary
atomic-red-team T1218.009.md Both utilities may be used to bypass application control through use of attributes within the binary to specify code that should be run before registration or unregistration: [ComRegisterFunction] or [ComUnregisterFunction] respectively. The code with the registration and unregistration attributes will be executed even if the process is run under insufficient privileges and fails to execute. (Citation: LOLBAS Regsvcs)(Citation: LOLBAS Regasm)</blockquote> MIT License. © 2018 Red Canary
atomic-red-team T1218.009.md - Atomic Test #1 - Regasm Uninstall Method Call Test MIT License. © 2018 Red Canary
atomic-red-team T1218.009.md ## Atomic Test #1 - Regasm Uninstall Method Call Test MIT License. © 2018 Red Canary
atomic-red-team T1218.009.md C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe /U #{output_file} MIT License. © 2018 Red Canary
signature-base apt_oilrig_oct17.yar $s2 = “C:\Windows\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe” fullword wide CC BY-NC 4.0

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