{
  "model_id": "SOC.056",
  "name": "File Made Immutable (chattr +i)",
  "description": "chattr used to set the immutable flag — prevents file modification even by root. Used to lock backdoors in place.",
  "threshold": 0.7,
  "evaluations": [
    {
      "name": "Chattr",
      "type": "comparison",
      "left": "event.raw.comm",
      "operator": "==",
      "right": "chattr",
      "weight": 4
    },
    {
      "name": "PlusI",
      "type": "comparison",
      "left": "event.raw.cmdline",
      "operator": "LIKE",
      "right": "%+i%",
      "weight": 5
    },
    {
      "name": "Logic",
      "type": "logical",
      "operator": "AND",
      "operands": [
        "Chattr",
        "PlusI"
      ],
      "weight": 5
    }
  ],
  "actions": [
    {
      "type": "emit_alert",
      "reason": "chattr +i used — file locked immutable. Common backdoor-protection technique."
    }
  ],
  "mitre_tactics": [
    "Defense Evasion"
  ],
  "mitre_techniques": [
    "T1222"
  ],
  "severity": "high",
  "observables": [
    "event.raw.cmdline"
  ]
}