Regsvr32 Execution From Highly Suspicious Location

detection:
  filter_main_empty:
    CommandLine: ''
  filter_main_null:
    CommandLine: null
  selection_exclude_known_dirs:
    CommandLine|contains:
      - 'C:\Program Files (x86)\'
      - 'C:\Program Files\'
      - 'C:\ProgramData\'
      - 'C:\Users\'
      - ' C:\Windows\'
      - ' "C:\Windows\'
      - ' ''C:\Windows\'
  selection_img:
    - Image|endswith: '\regsvr32.exe'
    - OriginalFileName: 'REGSVR32.EXE'
  selection_path_1:
    CommandLine|contains:
      - ':\PerfLogs\'
      - ':\Temp\'
      - '\Windows\Registration\CRMLog'
      - '\Windows\System32\com\dmp\'
      - '\Windows\System32\FxsTmp\'
      - '\Windows\System32\Microsoft\Crypto\RSA\MachineKeys\'
      - '\Windows\System32\spool\drivers\color\'
      - '\Windows\System32\spool\PRINTERS\'
      - '\Windows\System32\spool\SERVERS\'
      - '\Windows\System32\Tasks_Migrated\'
      - '\Windows\System32\Tasks\Microsoft\Windows\SyncCenter\'
      - '\Windows\SysWOW64\com\dmp\'
      - '\Windows\SysWOW64\FxsTmp\'
      - '\Windows\SysWOW64\Tasks\Microsoft\Windows\PLA\System\'
      - '\Windows\SysWOW64\Tasks\Microsoft\Windows\SyncCenter\'
      - '\Windows\Tasks\'
      - '\Windows\Tracing\'
  selection_path_2:
    CommandLine|contains:
      - ' "C:\'
      - ' C:\'
      - ' ''C:\'
      - 'D:\'
  condition: selection_img and (selection_path_1 or (selection_path_2 and not selection_exclude_known_dirs)) and not 1 of filter_main_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Nasreddine Bencherchali (Nextron Systems), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.