title: Excel Proxy Executing Regsvr32 With Payload
id: c0e1c3d5-4381-4f18-8145-2583f06a1fe5
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/main/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml
author: 'Vadim Khrykov (ThreatIntel), Cyb3rEng (Rule)'
tags:
    - attack.t1204.002
    - attack.t1047
    - attack.t1218.010
    - attack.execution
    - attack.defense_evasion
status: experimental
date: 2021/08/23
modified: 2021/11/09
logsource:
  product: windows
  category: process_creation
detection:
  #useful_information: add more LOLBins to the rules logic of your choice.
  selection1:
    ParentCommandLine:
      - '*regsvr32*'
      - '*rundll32*'
      - '*msiexec*'
      - '*mshta*'
      - '*verclsid*'
  selection2:
    - Image|endswith: '\wbem\WMIC.exe'
    - ParentCommandLine|contains: 'wmic '
  selection3:
    ParentImage|endswith:
      - winword.exe
      - excel.exe
      - powerpnt.exe
  selection4:
    ParentCommandLine|contains|all: 
      - 'process'
      - 'create'
      - 'call' 
  condition: selection1 and selection2 and selection3 and selection4
falsepositives:
- Unknown
level: high
