Potentially Suspicious Regsvr32 HTTP IP Pattern

SIGMA detection rule by Florian Roth (Nextron Systems) · NOASSERTION

Detects regsvr32 execution to download and install DLLs located remotely where the address is an IP address.

title: Potentially Suspicious Regsvr32 HTTP IP Pattern
id: 2dd2c217-bf68-437a-b57c-fe9fd01d5de8
status: test
description: Detects regsvr32 execution to download and install DLLs located remotely where the address is an IP address.
references:
    - https://twitter.com/mrd0x/status/1461041276514623491
    - https://twitter.com/tccontre18/status/1480950986650832903
    - https://lolbas-project.github.io/lolbas/Binaries/Regsvr32/
author: Florian Roth (Nextron Systems)
date: 2022-01-11
modified: 2023-05-24
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\regsvr32.exe'
        - OriginalFileName: 'REGSVR32.EXE'
    selection_ip:
        CommandLine|contains:
            - ' /i:http://1'
            - ' /i:http://2'
            - ' /i:http://3'
            - ' /i:http://4'
            - ' /i:http://5'
            - ' /i:http://6'
            - ' /i:http://7'
            - ' /i:http://8'
            - ' /i:http://9'
            - ' /i:https://1'
            - ' /i:https://2'
            - ' /i:https://3'
            - ' /i:https://4'
            - ' /i:https://5'
            - ' /i:https://6'
            - ' /i:https://7'
            - ' /i:https://8'
            - ' /i:https://9'
            - ' -i:http://1'
            - ' -i:http://2'
            - ' -i:http://3'
            - ' -i:http://4'
            - ' -i:http://5'
            - ' -i:http://6'
            - ' -i:http://7'
            - ' -i:http://8'
            - ' -i:http://9'
            - ' -i:https://1'
            - ' -i:https://2'
            - ' -i:https://3'
            - ' -i:https://4'
            - ' -i:https://5'
            - ' -i:https://6'
            - ' -i:https://7'
            - ' -i:https://8'
            - ' -i:https://9'
    condition: all of selection_*
falsepositives:
    - FQDNs that start with a number such as "7-Zip"
level: high

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758d6690-898f-4988-9dc0-708b695e40bb

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

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