{
  "id": "investigation-summary:1e80b94a-c04d-4688-b0ee-efdabd2760e1",
  "type": "pcap-investigation-summary",
  "label": "PCAP investigation summary",
  "model": "gpt-4.1-2025-04-14",
  "stale": false,
  "status": "analyst-review-required",
  "content": "# PCAP investigation summary\n\n## What happened\n\nThe host Escritorio-PC \\(172.16.5.203\\) participated in standard Kerberos authentication and directory protocol activity within a local network, involving accounts such as thiago.almeida and escritorio-pc$.\n\nDirectory protocol operations \\(LDAP, SAMR, DRSUAPI\\) were observed between Escritorio-PC and a domain controller \\(172.16.5.5\\), but this traffic matches normal Windows logon and user activity, with no evidence for credential theft, discovery, or DCSync.\n\n## Who was involved\n\n- The host Escritorio-PC \\(172.16.5.203\\) is associated with the accounts thiago.almeida and escritorio-pc$.\n- The account thiago.almeida is present as a Kerberos client principal.\n- The hostname Escritorio-PC is used by the device at 172.16.5.203.\n\n## What remains uncertain\n\n- There is no evidence of suspicious payload transfers, malware execution, or data exfiltration in this capture.\n\n## Next check\n\n- If investigation is warranted, review endpoint logs on Escritorio-PC for anomalies not detectable in network traffic alone.\n\nAnalyst-review draft. Exact evidence references and provider provenance are retained in the structured record.",
  "summary": "The host Escritorio-PC (172.16.5.203) participated in standard Kerberos authentication and directory protocol activity within a local network, involving accounts such as thiago.almeida and escritorio-pc$. Directory protocol operations (LDAP, SAMR, DRSUAPI) were observed between Escritorio-PC and a domain controller (172.16.5.5), but this traffic matches normal Windows logon and user activity, with no evidence for credential theft, discovery, or DCSync.",
  "coverage": {
    "warnings": [],
    "projection": "pcap-brief-evidence-v1",
    "source_digest": "03e2c9b3e57d15b0d9ee21708ce1150787da9c0e2cf90c43838bb46a951c14f4",
    "candidate_total": 0,
    "omitted_records": {
      "findings": 0,
      "artifacts": 5,
      "candidates": 0,
      "identities": 0,
      "techniques": 0,
      "selected_network_events": 0
    },
    "compact_evidence": false,
    "included_records": {
      "limits": 1,
      "capture": 1,
      "findings": 6,
      "identities": 4,
      "reputation_coverage": 1
    },
    "supplement_scope": "Bounded selected packet metadata, direct reputation, identities and transfer relationships; no payload bodies, prior-case content or exhaustive inventory. Full data remains in source analysis.",
    "source_characters": 4895,
    "enrichment_retained_targets": 18
  },
  "filename": "2018-09-27-traffic-analysis-exercise.pcap",
  "provider": "openai",
  "report_id": "pcap:0e0621ff-1831-43a5-b884-8ae7b2febaf3",
  "created_at": "2026-09-22T19:20:25.438792+00:00",
  "structured": {
    "iocs": [],
    "ttps": [],
    "identities": [
      {
        "kind": "ip",
        "text": "The host Escritorio-PC (172.16.5.203) is associated with the accounts thiago.almeida and escritorio-pc$.",
        "basis": "observed",
        "value": "172.16.5.203",
        "evidence": [
          {
            "end": 330,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":46,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"},{\"account\":\"\",\"frame_number\":54,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\"],\"type\":\"account\",\"value\":\"escritorio-pc$\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1bbc34e66d91dca4c3f3d499",
            "source_id": "S0004",
            "source_sha256": "c03a823cb44754e9e6f64fa2219e60a59e7cdc960b0f2972df6719ebcfc6b1ec"
          },
          {
            "end": 332,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":522,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"},{\"account\":\"\",\"frame_number\":530,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\"],\"type\":\"account\",\"value\":\"thiago.almeida\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-8134d8e2e6ae3875b853dab7",
            "source_id": "S0005",
            "source_sha256": "b08c54719eee9615398acb7ed05185b552f64266dbaf905b6caff59c47431dcd"
          },
          {
            "end": 352,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":383,\"owner_ip\":\"0.0.0.0\",\"relationship\":\"dhcp-client-assertion\"},{\"account\":\"\",\"frame_number\":697,\"owner_ip\":\"0.0.0.0\",\"relationship\":\"dhcp-client-assertion\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\",\"30:85:a9:f4:92:17,30:85:a9:f4:92:17\"],\"type\":\"hostname\",\"value\":\"Escritorio-PC\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1fb40620e1955c984c8b3d4c",
            "source_id": "S0006",
            "source_sha256": "5c5df4ca09e8fbef881ff4991ffef57fa661513e734991c1e98259bddf518055"
          }
        ]
      },
      {
        "kind": "account",
        "text": "The account thiago.almeida is present as a Kerberos client principal.",
        "basis": "observed",
        "value": "thiago.almeida",
        "evidence": [
          {
            "end": 332,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":522,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"},{\"account\":\"\",\"frame_number\":530,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\"],\"type\":\"account\",\"value\":\"thiago.almeida\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-8134d8e2e6ae3875b853dab7",
            "source_id": "S0005",
            "source_sha256": "b08c54719eee9615398acb7ed05185b552f64266dbaf905b6caff59c47431dcd"
          }
        ]
      },
      {
        "kind": "host",
        "text": "The hostname Escritorio-PC is used by the device at 172.16.5.203.",
        "basis": "observed",
        "value": "Escritorio-PC",
        "evidence": [
          {
            "end": 352,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":383,\"owner_ip\":\"0.0.0.0\",\"relationship\":\"dhcp-client-assertion\"},{\"account\":\"\",\"frame_number\":697,\"owner_ip\":\"0.0.0.0\",\"relationship\":\"dhcp-client-assertion\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\",\"30:85:a9:f4:92:17,30:85:a9:f4:92:17\"],\"type\":\"hostname\",\"value\":\"Escritorio-PC\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1fb40620e1955c984c8b3d4c",
            "source_id": "S0006",
            "source_sha256": "5c5df4ca09e8fbef881ff4991ffef57fa661513e734991c1e98259bddf518055"
          }
        ]
      }
    ],
    "next_steps": [
      {
        "text": "If investigation is warranted, review endpoint logs on Escritorio-PC for anomalies not detectable in network traffic alone.",
        "basis": "assessment",
        "evidence": [
          {
            "end": 397,
            "quote": "{\"internal_lookup\":{\"matched_observables\":0,\"no_exact_match\":50,\"observable_limit\":5000,\"observables_checked\":50,\"observables_total\":50,\"prior_case_limit_reached\":true,\"prior_cases_checked\":50,\"truncated\":false},\"visibility\":\"Encrypted application payloads are not decrypted. No endpoint execution, persistence or actor attribution is established by a download or connection alone.\",\"warnings\":[]}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#coverage",
            "source_id": "S0002",
            "source_sha256": "62acf32c4f3018d53732bb67aef6654592edc26c4f8365cdcee5484acef2b97f"
          }
        ]
      }
    ],
    "uncertainties": [
      {
        "text": "There is no evidence of suspicious payload transfers, malware execution, or data exfiltration in this capture.",
        "basis": "observed",
        "evidence": [
          {
            "end": 397,
            "quote": "{\"internal_lookup\":{\"matched_observables\":0,\"no_exact_match\":50,\"observable_limit\":5000,\"observables_checked\":50,\"observables_total\":50,\"prior_case_limit_reached\":true,\"prior_cases_checked\":50,\"truncated\":false},\"visibility\":\"Encrypted application payloads are not decrypted. No endpoint execution, persistence or actor attribution is established by a download or connection alone.\",\"warnings\":[]}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#coverage",
            "source_id": "S0002",
            "source_sha256": "62acf32c4f3018d53732bb67aef6654592edc26c4f8365cdcee5484acef2b97f"
          }
        ]
      }
    ],
    "what_happened": [
      {
        "text": "The host Escritorio-PC (172.16.5.203) participated in standard Kerberos authentication and directory protocol activity within a local network, involving accounts such as thiago.almeida and escritorio-pc$.",
        "basis": "observed",
        "evidence": [
          {
            "end": 330,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":46,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"},{\"account\":\"\",\"frame_number\":54,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\"],\"type\":\"account\",\"value\":\"escritorio-pc$\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1bbc34e66d91dca4c3f3d499",
            "source_id": "S0004",
            "source_sha256": "c03a823cb44754e9e6f64fa2219e60a59e7cdc960b0f2972df6719ebcfc6b1ec"
          },
          {
            "end": 332,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":522,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"},{\"account\":\"\",\"frame_number\":530,\"owner_ip\":\"172.16.5.203\",\"relationship\":\"kerberos-client-principal\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\"],\"type\":\"account\",\"value\":\"thiago.almeida\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-8134d8e2e6ae3875b853dab7",
            "source_id": "S0005",
            "source_sha256": "b08c54719eee9615398acb7ed05185b552f64266dbaf905b6caff59c47431dcd"
          },
          {
            "end": 352,
            "quote": "{\"bindings\":[{\"account\":\"\",\"frame_number\":383,\"owner_ip\":\"0.0.0.0\",\"relationship\":\"dhcp-client-assertion\"},{\"account\":\"\",\"frame_number\":697,\"owner_ip\":\"0.0.0.0\",\"relationship\":\"dhcp-client-assertion\"}],\"ip_addresses\":[\"172.16.5.203\"],\"mac_addresses\":[\"30:85:a9:f4:92:17\",\"30:85:a9:f4:92:17,30:85:a9:f4:92:17\"],\"type\":\"hostname\",\"value\":\"Escritorio-PC\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1fb40620e1955c984c8b3d4c",
            "source_id": "S0006",
            "source_sha256": "5c5df4ca09e8fbef881ff4991ffef57fa661513e734991c1e98259bddf518055"
          }
        ]
      },
      {
        "text": "Directory protocol operations (LDAP, SAMR, DRSUAPI) were observed between Escritorio-PC and a domain controller (172.16.5.5), but this traffic matches normal Windows logon and user activity, with no evidence for credential theft, discovery, or DCSync.",
        "basis": "assessment",
        "evidence": [
          {
            "end": 422,
            "quote": "{\"explanation\":\"Directory protocol operations were decoded. Normal Windows logon uses these protocols; activity alone does not establish discovery, credential theft, or DCSync.\",\"frames\":[244,246,248],\"metrics\":{\"destination\":\"172.16.5.5\",\"event_count\":16,\"operation_numbers\":[\"0\",\"1\",\"12\"],\"protocol\":\"drsuapi\",\"source\":\"172.16.5.203\"},\"rule_id\":\"directory-service-activity\",\"title\":\"Directory-service protocol activity\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-06298fef2fea9cad0002543e",
            "source_id": "S0008",
            "source_sha256": "abb55dcca5dfc23a28bfc5f4744e81dc2451831154118d40f83e8271128770b4"
          },
          {
            "end": 422,
            "quote": "{\"explanation\":\"Directory protocol operations were decoded. Normal Windows logon uses these protocols; activity alone does not establish discovery, credential theft, or DCSync.\",\"frames\":[245,247,249],\"metrics\":{\"destination\":\"172.16.5.203\",\"event_count\":16,\"operation_numbers\":[\"0\",\"1\",\"12\"],\"protocol\":\"drsuapi\",\"source\":\"172.16.5.5\"},\"rule_id\":\"directory-service-activity\",\"title\":\"Directory-service protocol activity\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-5a31de8fb0ddef12a7869654",
            "source_id": "S0009",
            "source_sha256": "7ac9f4978b121c1e5f559148130111f0bb7cbb993bdcbc0ace7085863c477a21"
          },
          {
            "end": 462,
            "quote": "{\"explanation\":\"Directory protocol operations were decoded. Normal Windows logon uses these protocols; activity alone does not establish discovery, credential theft, or DCSync.\",\"frames\":[22950,22952,22954],\"metrics\":{\"destination\":\"172.16.5.203\",\"event_count\":15,\"operation_numbers\":[\"1\",\"16\",\"17\",\"3\",\"34\",\"36\",\"39\",\"5\",\"6\",\"64\",\"7\"],\"protocol\":\"samr\",\"source\":\"172.16.5.5\"},\"rule_id\":\"directory-service-activity\",\"title\":\"Directory-service protocol activity\"}",
            "start": 0,
            "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-63715bcfd17746575730b78f",
            "source_id": "S0010",
            "source_sha256": "dffec00080aa4308a4a8e26d885e2e1377d271f337b324e68209e20ba9395c62"
          }
        ]
      }
    ]
  },
  "validation": "schema-and-exact-quote-binding; not semantic proof",
  "word_count": 123,
  "analysis_id": "0e0621ff-1831-43a5-b884-8ae7b2febaf3",
  "token_usage": {
    "total_tokens": 5356,
    "prompt_tokens": 4880,
    "completion_tokens": 476
  },
  "authoritative": false,
  "effective_tlp": "TLP:CLEAR",
  "source_sha256": "9bb0de3408b8ee7b3023246049ddd0af44a770b430045b69f5f097168020f253",
  "capture_sha256": "460b5e968641264ffb63486cfe2c6586c0db9e19fcc047175c978009eaa94d7b",
  "prompt_version": "pcap-investigation-summary-v5",
  "requested_model": "gpt-4.1",
  "source_manifest": [
    {
      "kind": "packet_fact",
      "offset": 0,
      "sha256": "eddc890edaa82677ae42568442bc54cb61c55d4e8b83f65e21dde89d9b7036b3",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#capture",
      "source_id": "S0001"
    },
    {
      "kind": "packet_fact",
      "offset": 0,
      "sha256": "62acf32c4f3018d53732bb67aef6654592edc26c4f8365cdcee5484acef2b97f",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#coverage",
      "source_id": "S0002"
    },
    {
      "kind": "intelligence_lead",
      "offset": 0,
      "sha256": "338a11bd6150adccee5b83f40b0275342d61d916ae6a5c94dc6a367b2bf97a56",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#enrichment-coverage",
      "source_id": "S0003"
    },
    {
      "kind": "packet_fact",
      "offset": 0,
      "sha256": "c03a823cb44754e9e6f64fa2219e60a59e7cdc960b0f2972df6719ebcfc6b1ec",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1bbc34e66d91dca4c3f3d499",
      "source_id": "S0004"
    },
    {
      "kind": "packet_fact",
      "offset": 0,
      "sha256": "b08c54719eee9615398acb7ed05185b552f64266dbaf905b6caff59c47431dcd",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-8134d8e2e6ae3875b853dab7",
      "source_id": "S0005"
    },
    {
      "kind": "packet_fact",
      "offset": 0,
      "sha256": "5c5df4ca09e8fbef881ff4991ffef57fa661513e734991c1e98259bddf518055",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-1fb40620e1955c984c8b3d4c",
      "source_id": "S0006"
    },
    {
      "kind": "packet_fact",
      "offset": 0,
      "sha256": "395ec7fc8af8d48f60517fbbdc143c4ff9a33b9d838c90a4afac2239cc71e787",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#identity/identity-314f0642a8971c5782177e6d",
      "source_id": "S0007"
    },
    {
      "kind": "rule_candidate",
      "offset": 0,
      "sha256": "abb55dcca5dfc23a28bfc5f4744e81dc2451831154118d40f83e8271128770b4",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-06298fef2fea9cad0002543e",
      "source_id": "S0008"
    },
    {
      "kind": "rule_candidate",
      "offset": 0,
      "sha256": "7ac9f4978b121c1e5f559148130111f0bb7cbb993bdcbc0ace7085863c477a21",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-5a31de8fb0ddef12a7869654",
      "source_id": "S0009"
    },
    {
      "kind": "rule_candidate",
      "offset": 0,
      "sha256": "dffec00080aa4308a4a8e26d885e2e1377d271f337b324e68209e20ba9395c62",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-63715bcfd17746575730b78f",
      "source_id": "S0010"
    },
    {
      "kind": "rule_candidate",
      "offset": 0,
      "sha256": "e74dce180303636894e947e4fafb6f8122a5e22d0a333e5e8963dd3ec6b02ab2",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-ad67bee1be87f4bb9cd629e8",
      "source_id": "S0011"
    },
    {
      "kind": "rule_candidate",
      "offset": 0,
      "sha256": "23aec639fec7dc7208de59fd883f5c635adc9ee45916dc441004b9f5aaf0b000",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-bf980fac87380dce382c52bb",
      "source_id": "S0012"
    },
    {
      "kind": "rule_candidate",
      "offset": 0,
      "sha256": "4132f66d9e4373a0188c8f47b48a76e21a4f5a25a6c9d46030578aaf1d07451a",
      "reference": "/api/pcap/analyses/0e0621ff-1831-43a5-b884-8ae7b2febaf3#finding/finding-d693d2c4ca209f602fa7ea38",
      "source_id": "S0013"
    }
  ],
  "token_usage_note": "Provider-reported counts when available; never estimated from character length.",
  "generation_seconds": 7.007,
  "generation_attempts": [
    {
      "attempt": 1,
      "validation": "passed",
      "token_usage": {
        "total_tokens": 5356,
        "prompt_tokens": 4880,
        "completion_tokens": 476,
        "prompt_tokens_details": {
          "audio_tokens": 0,
          "cached_tokens": 0
        },
        "completion_tokens_details": {
          "audio_tokens": 0,
          "reasoning_tokens": 0,
          "accepted_prediction_tokens": 0,
          "rejected_prediction_tokens": 0
        }
      },
      "finish_reason": "stop",
      "provider_returned_model": "gpt-4.1-2025-04-14"
    }
  ],
  "validation_adjustments": [
    {
      "basis": "assessment",
      "index": 1,
      "action": "evidence-level-downgrade",
      "section": "what_happened"
    }
  ],
  "provider_returned_model": "gpt-4.1-2025-04-14"
}