MITRE ATT&CK Technique
Description
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) Adversaries can use Regsvcs and Regasm to proxy execution of code through a trusted Windows utility. Both utilities may be used to bypass process whitelisting through use of attributes within the binary to specify code that should be run before registration or unregistration: <code>[ComRegisterFunction]</code> or <code>[ComUnregisterFunction]</code> 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)
Supported Platforms
Created
April 29, 2026
Last Updated
April 29, 2026
STIX Data
{'created': '2017-05-31T21:31:33.499Z',
'created_by_ref': 'identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5',
'description': '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)\n'
'\n'
'Adversaries can use Regsvcs and Regasm to proxy execution of '
'code through a trusted Windows utility. Both utilities may be '
'used to bypass process whitelisting through use of attributes '
'within the binary to specify code that should be run before '
'registration or unregistration: '
'<code>[ComRegisterFunction]</code> or '
'<code>[ComUnregisterFunction]</code> 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)',
'external_references': [{'external_id': 'T1121',
'source_name': 'mitre-attack',
'url': 'https://attack.mitre.org/techniques/T1121'},
{'description': 'Microsoft. (n.d.). Regsvcs.exe (.NET '
'Services Installation Tool). '
'Retrieved July 1, 2016.',
'source_name': 'MSDN Regsvcs',
'url': 'https://msdn.microsoft.com/en-us/library/04za0hca.aspx'},
{'description': 'Microsoft. (n.d.). Regasm.exe '
'(Assembly Registration Tool). '
'Retrieved July 1, 2016.',
'source_name': 'MSDN Regasm',
'url': 'https://msdn.microsoft.com/en-us/library/tzat5yw6.aspx'},
{'description': 'LOLBAS. (n.d.). Regsvcs.exe. '
'Retrieved July 31, 2019.',
'source_name': 'LOLBAS Regsvcs',
'url': 'https://lolbas-project.github.io/lolbas/Binaries/Regsvcs/'},
{'description': 'LOLBAS. (n.d.). Regasm.exe. '
'Retrieved July 31, 2019.',
'source_name': 'LOLBAS Regasm',
'url': 'https://lolbas-project.github.io/lolbas/Binaries/Regasm/'}],
'id': 'attack-pattern--215190a9-9f02-4e83-bb5f-e0589965a302',
'kill_chain_phases': [{'kill_chain_name': 'mitre-attack',
'phase_name': 'defense-evasion'},
{'kill_chain_name': 'mitre-attack',
'phase_name': 'execution'}],
'modified': '2025-10-24T17:48:30.868Z',
'name': 'Regsvcs/Regasm',
'object_marking_refs': ['marking-definition--fa42a846-8d90-4e51-bc29-71d5b4802168'],
'revoked': True,
'spec_version': '2.1',
'type': 'attack-pattern',
'x_mitre_attack_spec_version': '3.2.0',
'x_mitre_contributors': ['Casey Smith'],
'x_mitre_deprecated': False,
'x_mitre_detection': '',
'x_mitre_domains': ['enterprise-attack'],
'x_mitre_is_subtechnique': False,
'x_mitre_modified_by_ref': 'identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5',
'x_mitre_platforms': ['Windows'],
'x_mitre_version': '1.3'}