RegAsm.exe

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

Hashes

Type Hash
MD5 0D5DF43AF2916F47D00C1573797C1A13
SHA1 230AB5559E806574D26B4C20847C368ED55483B0
SHA256 C066AEE7AA3AA83F763EBC5541DAA266ED6C648FBFFCDE0D836A13B221BB2ADC
SHA384 3B4D3715DC2C5CC65579F673250BB355D5B9590ECAB1BE1E2F845090E5482CEC6C05D9DD7167B39FEA785B1850EFA498
SHA512 F96CF9E1890746B12DAF839A6D0F16F062B72C1B8A40439F96583F242980F10F867720232A6FA0F7D4D7AC0A7A6143981A5A130D6417EA98B181447134C7CFE2
SSDEEP 768:X8XcJiMjm2ieHlPyCsSuJbn8dBhFwlSMF6Iq8KSYDKbQ22qWqO8w1R:rYMaNylPYSAb8dBnsHsPDKbQBqTY
IMP F34D5F2D4577ED6D9CEEC516C1F5A744
PESHA1 045ADCAA09C5A7BE1AB28595CDEF3EB76103573A
PE256 1D9DF24BC73C37A5CD72E6E4090260B968EBD50C4A74035C02851F46A118B515

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\Framework\v4.0.30319\RegAsm.exe
C:\Windows\SYSTEM32\ntdll.dll
C:\Windows\System32\wow64.dll
C:\Windows\System32\wow64cpu.dll
C:\Windows\System32\wow64win.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: 32-bit

File Scan

  • VirusTotal Detections: 0/73
  • VirusTotal Link: https://www.virustotal.com/gui/file/c066aee7aa3aa83f763ebc5541daa266ed6c648fbffcde0d836a13b221bb2adc/detection

File Similarity (ssdeep match)

File Score
C:\Windows\Microsoft.NET\Framework64\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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