Excel Proxy Executing Regsvr32 With Payload Alternate

SIGMA detection rule by Vadim Khrykov (ThreatIntel), Cyb3rEng (Rule) · GPL-2.0

Excel called wmic to finally proxy execute regsvr32 with the payload. An attacker wanted to break suspicious parent-child chain (Office app spawns LOLBin). But we have command-line in the event which allow us to "restore" this suspicious parent-child chain and detect it. Monitor process creation with "wmic process call create" and LOLBins in command-line with parent Office application processes.

title: Excel Proxy Executing Regsvr32 With Payload Alternate
id: 9b2384e8-4067-f192-274f-73d711fc193f
related:
    - id: c0e1c3d5-4381-4f18-8145-2583f06a1fe5
      type: derived
status: deprecated
description: |
    Excel called wmic to finally proxy execute regsvr32 with the payload.
    An attacker wanted to break suspicious parent-child chain (Office app spawns LOLBin).
    But we have command-line in the event which allow us to "restore" this suspicious parent-child chain and detect it.
    Monitor process creation with "wmic process call create" and LOLBins in command-line with parent Office application processes.
references:
    - https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/
    - https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml
author: Vadim Khrykov (ThreatIntel), Cyb3rEng (Rule)
date: 2021-08-23
modified: 2022-12-02
tags:
    - attack.t1204.002
    - attack.t1047
    - attack.t1218.010
    - attack.execution
    - attack.defense-evasion
logsource:
    product: windows
    category: process_creation
detection:
    process_creation:
        EventID: 4688
        Channel: Security
    selection1:
        CommandLine|contains:
            - regsvr32
            - rundll32
            - msiexec
            - mshta
            - verclsid
    selection2:
        - NewProcessName|endswith: \wbem\WMIC.exe
        - CommandLine|contains: 'wmic '
    selection3:
        ParentProcessName|endswith:
            - \winword.exe
            - \excel.exe
            - \powerpnt.exe
    selection4:
        CommandLine|contains|all:
            - process
            - create
            - call
    condition: process_creation and (all of selection*)
falsepositives:
    - Unknown
level: high
ruletype: Sigma

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

7984aa94-f1c5-411e-94a8-227dce0993a6

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Executable code, not a declarative rule

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