Regasm.exe

Loads the target .NET DLL file and executes the RegisterClass function.

Use Execute code and bypass Application whitelisting

regasm.exe {PATH:.dll}

Evidence

Upstream reference

Environment

Local host

Context

admin

Native

AWL Bypass

MITRE

T1218.009

Detection

Sigma: github.com/SigmaHQ/sigma/blob/6312dd1d44d309608552105c334948f793e89f48/rules/windows/process_creation/proc_creation_win_lolbin_regasm.yml

Elastic: github.com/elastic/detection-rules/blob/12577f7380f324fcee06dab3218582f4a11833e7/rules/windows/execution_register_server_program_connecting_to_the_internet.toml

Splunk: github.com/splunk/security_content/blob/bc93e670f5dcb24e96fbe3664d6bcad92df5acad/docs/_stories/suspicious_regsvcs_regasm_activity.md

Splunk: github.com/splunk/security_content/blob/bee2a4cefa533f286c546cbe6798a0b5dec3e5ef/detections/endpoint/detect_regasm_with_network_connection.yml

IOC: regasm.exe executing dll file

Refs

pentestlab.blog/2017/05/19/applocker-bypass-regasm-and-regsvcs/

oddvar.moe/2017/12/13/applocker-case-study-how-insecure-is-it-really-part-1/

github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.009/T1218.009.md

lolbas-project.github.io/lolbas/Binaries/Regasm/

Loads the target .DLL file and executes the UnRegisterClass function.

Use Execute code and bypass Application whitelisting

regasm.exe /U {PATH:.dll}

Evidence

Upstream reference

Environment

Local host

Context

user

Native

Execute

MITRE

T1218.009

Detection

Sigma: github.com/SigmaHQ/sigma/blob/6312dd1d44d309608552105c334948f793e89f48/rules/windows/process_creation/proc_creation_win_lolbin_regasm.yml

Elastic: github.com/elastic/detection-rules/blob/12577f7380f324fcee06dab3218582f4a11833e7/rules/windows/execution_register_server_program_connecting_to_the_internet.toml

Splunk: github.com/splunk/security_content/blob/bc93e670f5dcb24e96fbe3664d6bcad92df5acad/docs/_stories/suspicious_regsvcs_regasm_activity.md

Splunk: github.com/splunk/security_content/blob/bee2a4cefa533f286c546cbe6798a0b5dec3e5ef/detections/endpoint/detect_regasm_with_network_connection.yml

IOC: regasm.exe executing dll file

Refs

pentestlab.blog/2017/05/19/applocker-bypass-regasm-and-regsvcs/

oddvar.moe/2017/12/13/applocker-case-study-how-insecure-is-it-really-part-1/

github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.009/T1218.009.md

lolbas-project.github.io/lolbas/Binaries/Regasm/