Hayabusa high test sigma

LSASS Access Detected via Attack Surface Reduction

Detects Access to LSASS Process

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Detection Logic

{
  "windefend": {
    "Channel": "Microsoft-Windows-Windows Defender/Operational"
  },
  "selection": {
    "EventID": 1121,
    "Path
| endswith": "\\lsass.exe"
  },
  "filter_thor": {
    "ProcessName
| startswith": "C:\\Windows\\Temp\\asgard2-agent\\",
    "ProcessName
| endswith": [
      "\\thor64.exe",
      "\\thor.exe"
    ]
  },
  "filter_exact": {
    "ProcessName": [
      "C:\\Windows\\System32\\atiesrxx.exe",
      "C:\\Windows\\System32\\CompatTelRunner.exe",
      "C:\\Windows\\System32\\msiexec.exe",
      "C:\\Windows\\System32\\nvwmi64.exe",
      "C:\\Windows\\System32\\svchost.exe",
      "C:\\Windows\\System32\\Taskmgr.exe",
      "C:\\Windows\\System32\\wbem\\WmiPrvSE.exe",
      "C:\\Windows\\SysWOW64\\msiexec.exe"
    ]
  },
  "filter_begins": {
    "ProcessName
| startswith": [
      "C:\\Windows\\System32\\DriverStore\\",
      "C:\\WINDOWS\\Installer\\",
      "C:\\Program Files\\",
      "C:\\Program Files (x86)\\"
    ]
  },
  "condition": "windefend and (selection and not 1 of filter_*)"
}

False Positives

  • Google Chrome GoogleUpdate.exe
  • Some Taskmgr.exe related activity

Field Validations

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