title: Potentially Suspicious Execution Of Regasm/Regsvcs From Uncommon Location
id: cc368ed0-2411-45dc-a222-510ace303cb2
related:
    - id: e9f8f8cc-07cc-4e81-b724-f387db9175e4
      type: derived
status: test
description: Detects potentially suspicious execution of the Regasm/Regsvcs utilities from a potentially suspicious location
references:
    - https://www.fortiguard.com/threat-signal-report/4718?s=09
    - https://lolbas-project.github.io/lolbas/Binaries/Regasm/
    - https://lolbas-project.github.io/lolbas/Binaries/Regsvcs/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-25
modified: 2023-02-13
tags:
    - attack.stealth
    - attack.t1218.009
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\Regsvcs.exe'
              - '\Regasm.exe'
        - OriginalFileName:
              - 'RegSvcs.exe'
              - 'RegAsm.exe'
    selection_dir:
        CommandLine|contains:
            # Note: Add more potentially suspicious directories
            - '\AppData\Local\Temp\'
            - '\Microsoft\Windows\Start Menu\Programs\Startup\'
            - '\PerfLogs\'
            - '\Users\Public\'
            - '\Windows\Temp\'
            # - '\Desktop\'
            # - '\Downloads\'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

title: Potentially Suspicious Execution Of Regasm/Regsvcs With Uncommon Extension
id: e9f8f8cc-07cc-4e81-b724-f387db9175e4
related:
    - id: cc368ed0-2411-45dc-a222-510ace303cb2
      type: derived
status: test
description: Detects potentially suspicious execution of the Regasm/Regsvcs utilities with an uncommon extension.
references:
    - https://www.fortiguard.com/threat-signal-report/4718?s=09
    - https://lolbas-project.github.io/lolbas/Binaries/Regasm/
    - https://lolbas-project.github.io/lolbas/Binaries/Regsvcs/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-02-13
tags:
    - attack.stealth
    - attack.t1218.009
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\Regsvcs.exe'
              - '\Regasm.exe'
        - OriginalFileName:
              - 'RegSvcs.exe'
              - 'RegAsm.exe'
    selection_extension:
        CommandLine|contains:
            # Note: Add more potentially uncommon extensions
            - '.dat'
            - '.gif'
            - '.jpeg'
            - '.jpg'
            - '.png'
            - '.txt'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

title: RegAsm.EXE Initiating Network Connection To Public IP
id: 0531e43a-d77d-47c2-b89f-5fe50321c805
status: test
description: Detects "RegAsm.exe" initiating a network connection to public IP adresses
references:
    - https://app.any.run/tasks/ec207948-4916-47eb-a0f4-4c6abb2e7668/
    - https://research.splunk.com/endpoint/07921114-6db4-4e2e-ae58-3ea8a52ae93f/
    - https://lolbas-project.github.io/lolbas/Binaries/Regasm/
author: frack113
date: 2024-04-25
tags:
    - attack.stealth
    - attack.t1218.009
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        Image|endswith: '\regasm.exe'
    filter_main_local_ranges:
        DestinationIp|cidr:
            - '127.0.0.0/8'
            - '10.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '169.254.0.0/16'
            - '::1/128'  # IPv6 loopback
            - 'fe80::/10'  # IPv6 link-local addresses
            - 'fc00::/7'  # IPv6 private addresses
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

title: RegAsm.EXE Execution Without CommandLine Flags or Files
id: 651f87f7-12db-47f9-84c5-f27b081b94b6
status: experimental
description: |
    Detects the execution of "RegAsm.exe" without a commandline flag or file, which might indicate potential process injection activity.
    Usually "RegAsm.exe" should point to a dedicated DLL file or call the help with the "/?" flag.
references:
    - https://www.mcafee.com/blogs/other-blogs/mcafee-labs/agent-teslas-unique-approach-vbs-and-steganography-for-delivery-and-intrusion/
    - https://www.zscaler.fr/blogs/security-research/threat-actors-exploit-cve-2017-11882-deliver-agent-tesla
    - https://learn.microsoft.com/en-us/dotnet/framework/tools/regasm-exe-assembly-registration-tool
    - https://app.any.run/tasks/ea944b89-69d8-49c8-ac1f-5c76ad300db2
    - https://www.joesandbox.com/analysis/1467354/0/html
author: frack113
date: 2025-06-04
tags:
    - attack.stealth
    - attack.t1218.009
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\RegAsm.exe'
        - OriginalFileName: 'RegAsm.exe'
    selection_cli:
        CommandLine|endswith:
            - 'RegAsm'
            - 'RegAsm.exe'
            - 'RegAsm.exe"'
            - "RegAsm.exe'"
    condition: all of selection_*
falsepositives:
    - Legitimate use of Regasm by developers.
# Note: You can increase after an initial baseline
level: low