{
  "author": "ckeller@fusioncybersecurity.us",
  "cat": "New Code Atypical Path",
  "detect": {
    "event": {
      "FILE_PATH": "C:\\Windows\\Temp\\{5C005CE4-9613-4823-827F-CB0CF57F03F8}\\.be\\VC_redist.x64.exe",
      "HASH": "568c9ba533624084ea18f7a562b4aa2249ed4e41281524a061a0d0b1008cf6bd",
      "PROCESS_ID": 2640
    },
    "routing": {
      "arch": 2,
      "did": "",
      "event_id": "29beb0c2-4390-4c59-a7a1-025261660186",
      "event_time": 1774799479698,
      "event_type": "NEW_DOCUMENT",
      "ext_ip": "23.128.32.10",
      "hostname": "desktop-3nfb237",
      "iid": "b2cd59fc-d09d-49e0-a9f2-1fd79ee9c175",
      "int_ip": "192.168.50.40",
      "latency": 989,
      "moduleid": 2,
      "oid": "d3541070-8b0e-4663-8a6a-aa0727aacd36",
      "parent": "6315a1641006ebfebc1bfe8b69c94a71",
      "plat": 268435456,
      "sid": "ed8f7c3f-3a1a-493e-8fa4-35eb8c30b136",
      "tags": [
        "fusion-soc-alert",
        "fusion-soc-case",
        "fusion-soc-pulled",
        "fusion-soc-triage",
        "fusionsoc-critical",
        "fusionsoc-high",
        "fusionsoc-investigated",
        "qucikbooks",
        "windows",
        "yara_detection_memory"
      ],
      "this": "381f57cbae2f214fa7f3fc8469c94a78"
    }
  },
  "detect_id": "347c4720-c25a-4364-a5df-548169c94a78",
  "gen_time": 1774799480688,
  "link": "https://app.limacharlie.io/orgs/d3541070-8b0e-4663-8a6a-aa0727aacd36/sensors/ed8f7c3f-3a1a-493e-8fa4-35eb8c30b136/timeline?time=1774799479\u0026selected=381f57cbae2f214fa7f3fc8469c94a78",
  "namespace": "general",
  "routing": {
    "arch": 2,
    "did": "",
    "event_id": "29beb0c2-4390-4c59-a7a1-025261660186",
    "event_time": 1774799479698,
    "event_type": "NEW_DOCUMENT",
    "ext_ip": "23.128.32.10",
    "hostname": "desktop-3nfb237",
    "iid": "b2cd59fc-d09d-49e0-a9f2-1fd79ee9c175",
    "int_ip": "192.168.50.40",
    "latency": 989,
    "moduleid": 2,
    "oid": "d3541070-8b0e-4663-8a6a-aa0727aacd36",
    "parent": "6315a1641006ebfebc1bfe8b69c94a71",
    "plat": 268435456,
    "sid": "ed8f7c3f-3a1a-493e-8fa4-35eb8c30b136",
    "tags": [
      "fusion-soc-alert",
      "fusion-soc-case",
      "fusion-soc-pulled",
      "fusion-soc-triage",
      "fusionsoc-critical",
      "fusionsoc-high",
      "fusionsoc-investigated",
      "qucikbooks",
      "windows",
      "yara_detection_memory"
    ],
    "this": "381f57cbae2f214fa7f3fc8469c94a78"
  },
  "source": "d3541070-8b0e-4663-8a6a-aa0727aacd36.b2cd59fc-d09d-49e0-a9f2-1fd79ee9c175.ed8f7c3f-3a1a-493e-8fa4-35eb8c30b136.10000000.2",
  "source_rule": "general.NEW FILE WRITE BYTES SAMPLE GRAB",
  "ts": 1774799480000
}

{
  "virustotal": {
    "malicious": false,
    "provider": "virustotal",
    "reputation": 0,
    "stats": {
      "confirmed-timeout": 0,
      "failure": 0,
      "harmless": 0,
      "malicious": 0,
      "suspicious": 0,
      "timeout": 1,
      "type-unsupported": 4,
      "undetected": 71
    }
  }
}

{
  "confidence": 0.965,
  "false_positive_reason": "Legitimate Microsoft Visual C++ Redistributable installer staged in temporary directory during software update or installation. Historical rule performance indicates 100% false positive rate for this pattern.",
  "investigation_questions": [
    "Was a software update or application installation initiated by the user or IT recently?",
    "Is the host managed by SCCM or Intune which may deploy redistributables automatically?"
  ],
  "ioc_analysis": "VC_redist.x64.exe is a known legitimate Microsoft binary used for runtime library installation. The path C:\\Windows\\Temp\\{GUID} is a standard staging location for software updates and deployment tools. No malicious indicators such as unsigned hashes or suspicious process trees were observed.",
  "iocs_extracted": [
    "C:\\Windows\\Temp\\{5C005CE4-9613-4823-827F-CB0CF57F03F8}\\.be\\VC_redist.x64.exe",
    "568c9ba533624084ea18f7a562b4aa2249ed4e41281524a061a0d0b1008cf6bd"
  ],
  "mitre_techniques": [],
  "recommended_actions": [
    "Manual analyst review required \u2014 AI models (unanimous)",
    "Verify if a software installation or update was expected on this host",
    "Add rule exception for VC_redist.x64.exe in Temp directories if confirmed benign"
  ],
  "risk_score": 6,
  "severity": "high",
  "summary": "**Vote: UNANIMOUS (2/2 -\u003e FALSE POSITIVE)**\n\n### \ud83e\udde0 dgx-122b Analysis (Primary)\n**Verdict:** false_positive | **Confidence:** 0.95\nThe event detects a Microsoft Visual C++ Redistributable installer staged in a temporary directory. Historical analysis of this specific detection rule shows a 100% false positive rate for similar temporary file writes involving legitimate software components.\n\n**IOC Analysis:** VC_redist.x64.exe is a known legitimate Microsoft binary used for runtime library installation. The path C:\\Windows\\Temp\\{GUID} is a standard staging location for software updates and deployment tools. No malicious indicators such as unsigned hashes or suspicious process trees were observed.\n\n---\n\n### \ud83e\udd16 qwen3.5:4b Analysis (Secondary)\nFailed or timed out.\n\n---\n\n### \ud83e\udd16 deepseek-r1:14b Analysis (Secondary)\nFailed or timed out.\n\n---\n\n### \ud83e\udd16 gemma3:4b Analysis (Secondary + RAG)\n**Verdict:** false_positive | **Confidence:** 0.98\nThe detection involves a Microsoft Visual C++ Redistributable installer written to a temporary directory. Historical analysis and automated investigation findings confirm this behavior is consistent with legitimate software updates and is a known false positive for this detection rule.\n\n**IOC Analysis:** The file `VC_redist.x64.exe` is a Microsoft-signed binary, and its presence in the C:\\Windows\\Temp directory is a standard staging location for Windows updates. The process tree shows it running from the expected location and with benign command-line arguments.",
  "verdict": "false_positive",
  "voting": {
    "auto_action": "manual_review",
    "mode": "unanimous",
    "total_models": 2,
    "vote_summary": [
      "dgx-122b: false_positive (low, 95% confidence)",
      "gemma3:4b +RAG: false_positive (low, 98% confidence)"
    ],
    "votes": [
      {
        "confidence": 0.95,
        "model": "dgx-122b",
        "verdict": "false_positive"
      },
      {
        "confidence": 0.98,
        "had_rag": true,
        "model": "gemma3:4b",
        "verdict": "false_positive"
      }
    ],
    "winning_count": 2,
    "winning_verdict": "false_positive"
  }
}