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T0885 Commonly Used Port — Attack Simulation

Adversaries may communicate over a commonly used port to bypass firewalls or network detection systems and to blend in with normal network activity, to avoid more detailed inspection. They may use the protocol associated with the port, or a completely different protocol. They may use commonly open ports, such as the examples provided below. * TCP:80 (HTTP) * TCP:443 (HTTPS) * TCP/UDP:53 (DNS) * TCP:1024-4999 (OPC on XP/Win2k3) * TCP:49152-65535…

Complete technique description

Adversaries may communicate over a commonly used port to bypass firewalls or network detection systems and to blend in with normal network activity, to avoid more detailed inspection. They may use the protocol associated with the port, or a completely different protocol. They may use commonly open ports, such as the examples provided below.

* TCP:80 (HTTP)
* TCP:443 (HTTPS)
* TCP/UDP:53 (DNS)
* TCP:1024-4999 (OPC on XP/Win2k3)
* TCP:49152-65535 (OPC on Vista and later)
* TCP:23 (TELNET)
* UDP:161 (SNMP)
* TCP:502 (MODBUS)
* TCP:102 (S7comm/ISO-TSAP)
* TCP:20000 (DNP3)
* TCP:44818 (Ethernet/IP)

Official technique definition · Open in the interactive matrix

Detection telemetry and configuration

These contracts are selected through exact technique-to-data-component relationships or explicitly labelled planning overrides. Configure a collector at the relevant observation point; a telemetry name alone is not coverage.

Network Connection Creation · source-mapped

DC0082 collection page — Enable scoped Sysmon NetworkConnect (3), disabled by default, or a platform-equivalent process-aware network sensor.

Providers and collection configuration

  • Microsoft Sysmon: Windows event-based collection; enable the event types needed below.
  • Linux Audit: Linux alternative for supported system-call and file events; different semantics and fields.
  • Apple Endpoint Security clients: macOS alternative where the subscribed event exists; requires an entitled, approved client, not an iOS collector.
  • On a disposable Windows host, review the installed Sysmon schema and current configuration; merge scoped event filters into the existing policy rather than replacing it.
  • Forward Microsoft-Windows-Sysmon/Operational to the lab collector. Preserve event ID, timestamp, computer, process identifiers and the original event.
  • For Linux or macOS, select the equivalent sensor separately and test its emitted fields; a Windows event ID does not transfer across platforms.

Required normalized fields: process_guid, destination_ip, destination_port, protocol, initiated.

Illustrative collection event

Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.

{
  "schema": "1200km.telemetry.example.v1",
  "synthetic": true,
  "timestamp": "2026-09-27T12:00:00Z",
  "telemetry_id": "DC0082",
  "collector": "illustrative-lab-collector",
  "observation": {
    "process_guid": "lab-process-001",
    "destination_ip": "198.51.100.20",
    "destination_port": 443,
    "protocol": "tcp",
    "initiated": true
  }
}

Visibility limits: Event filtering and sensor versions change coverage. High-volume image-load and process-access collection needs tuning; endpoint events alone do not establish intent.

Network Traffic Content · source-mapped

DC0085 collection page — Scope approved packet capture/protocol content collection to the lab flow; retain capture provenance and truncation indicators.

Providers and collection configuration

  • Zeek: Connection and protocol metadata from traffic visible to the sensor.
  • Suricata EVE: Configured flow, alert, DNS, HTTP, TLS and protocol records.
  • Use an authorized lab TAP/SPAN, virtual mirror or gateway interface. Define which traffic crosses it; avoid assuming visibility into every segment.
  • Enable the required Zeek analyzers or Suricata EVE event types. Export logs with sensor identity, clock synchronization and flow correlation identifiers.
  • Monitor capture loss, truncation and exporter sampling. Capture payload only with approval and restrictive retention; encryption normally prevents plaintext inspection.

Required normalized fields: flow_id, protocol, method, path, payload_excerpt.

Illustrative collection event

Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.

{
  "schema": "1200km.telemetry.example.v1",
  "synthetic": true,
  "timestamp": "2026-09-27T12:00:00Z",
  "telemetry_id": "DC0085",
  "collector": "illustrative-lab-collector",
  "observation": {
    "flow_id": "lab-flow-1",
    "protocol": "http",
    "method": "GET",
    "path": "/lab-check",
    "payload_excerpt": "LAB_TELEMETRY_CHECK"
  }
}

Visibility limits: Flows are not packet payloads. NAT, asymmetric routes, encryption, missing mirrors and sampling can hide attribution or content. A destination connection alone does not prove malicious intent.

Network Traffic Flow · source-mapped

DC0078 collection page — Collect Zeek conn.log, Suricata flow events or exporter equivalents, including observation point and sampling settings.

Providers and collection configuration

  • Zeek: Connection and protocol metadata from traffic visible to the sensor.
  • Suricata EVE: Configured flow, alert, DNS, HTTP, TLS and protocol records.
  • AWS VPC Flow Logs: IP traffic metadata alternative; no packet payload or DNS answer history, and some traffic is not logged.
  • Use an authorized lab TAP/SPAN, virtual mirror or gateway interface. Define which traffic crosses it; avoid assuming visibility into every segment.
  • Enable the required Zeek analyzers or Suricata EVE event types. Export logs with sensor identity, clock synchronization and flow correlation identifiers.
  • Monitor capture loss, truncation and exporter sampling. Capture payload only with approval and restrictive retention; encryption normally prevents plaintext inspection.

Required normalized fields: source_ip, destination_ip, destination_port, protocol, bytes_sent, bytes_received.

Illustrative collection event

Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.

{
  "schema": "1200km.telemetry.example.v1",
  "synthetic": true,
  "timestamp": "2026-09-27T12:00:00Z",
  "telemetry_id": "DC0078",
  "collector": "illustrative-lab-collector",
  "observation": {
    "source_ip": "192.0.2.10",
    "destination_ip": "198.51.100.20",
    "destination_port": 443,
    "protocol": "tcp",
    "bytes_sent": 128,
    "bytes_received": 512
  }
}

Visibility limits: Flows are not packet payloads. NAT, asymmetric routes, encryption, missing mirrors and sampling can hide attribution or content. A destination connection alone does not prove malicious intent.

Detection rules and analytic guidance

Open the dedicated detection workspace · Existing query engineering

DET0736 Detection of Commonly Used Port

MITRE detection strategy

AN1869 Analytic 1869

Real-time monitoring identifies an Industrial Control System (ICS) host or server establishing outbound connections on a commonly-allowed port (e.g., 443, 80, 8080, 53, etc.) to a destination not in the approved vendor/business domain list, where that host's documented network role does not require external connectivity. Documented real-world use: Sandworm's 2015 Ukraine power grid attack used port 443 for Command and Control (C2) communications. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity. SNI and certificate attributes are TLS/session metadata; do not treat them as decrypted payload content. Encrypted application content requires a separate inspection point.

Platforms: Network Devices.

  • Network Traffic Flow — netflow:ipfix; channel IPFIX/NetFlow flow record (src/dst IP, src/dst port, protocol, packets/bytes/time): egress flow on port 443/80/8080/53 from Industrial Control Systems (ICS) host in no-external-connectivity role list to destination not in approved vendor domains.
  • Network Traffic Content — zeek:ssl; channel Transport Layer Security (TLS) Server Name Indication (SNI) or certificate issuer does not match approved vendor domains or recognized Content Delivery Network (CDN) serving vendor content.

AN2129 Analytic 2129

Real-time monitoring identifies an Industrial Control System (ICS) Linux service process initiating an outbound connection on a commonly-used port to a destination not in the approved vendor domain list. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Platforms: Linux.

  • Network Connection Creation — auditd:SYSCALL; channel Linux Audit SYSCALL/EXECVE/SOCKADDR records (configured audit rule): connect() syscall on port (e.g., 80, 443, 8080, etc.) to destination not in approved vendor domains, from Industrial Control Systems (ICS) service process.

AN2221 Analytic 2221

Real-time monitoring identifies an embedded field device initiating outbound connections on a commonly-used port to a destination outside the device's documented operational communication profile, which for most embedded Industrial Control System (ICS) devices normally should not include arbitrary outbound internet connectivity under the approved communications architecture. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Platforms: Embedded.

  • Network Traffic Flow — NSM:Connections; channel embedded device_ip initiates outbound connection on port 443/80/8080 to destination outside documented operational profile.

AN2271 Analytic 2271

Real-time monitoring identifies an Industrial Control System (ICS) vendor process making outbound connections on commonly-allowed port (e.g., 80, 443, 8080, etc.) to a destination not in the approved vendor domain list, from a host whose documented role does not require external connectivity. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Platforms: Windows.

  • Network Connection Creation — WinEventLog:Sysmon; channel EventCode=3 on port 80/443/8080 from process not matching Industrial Control Systems (ICS) vendor update process allowlist.
Source rule directory and observation requirements

No exact-tagged Sigma source rule was imported. This does not establish that the technique is undetectable; the MITRE guidance and collection requirements remain relevant.

Before treating a rule as coverage

  1. Read the actual condition and logsource; identify attacker-side, victim-side or third-party visibility.
  2. Map native sensor fields, parse times and identities, then compile for the selected backend.
  3. Replay a behavior-positive case, a normal control, an authorized look-alike and a missing-telemetry case.
  4. Record matches and misses with rule version and source events. No match is inconclusive when required telemetry is absent.

Anomaly-based detection

No exact technique-specific Atlas model is present for T0885 in the selected source snapshot. The following is a design worksheet, not a newly validated model.

Anomaly engineering worksheet

Start from the exact analytic above. The collection-specific lenses below are analyst recommendations; they do not assert that an arbitrary statistical deviation detects this technique.

  • Endpoint activity: Per host role and user: rare process/object combinations, bursts of object access or modification, and ordered parent/action sequences. Compare maintenance windows and signed software rollout activity.
  • Network and protocol telemetry: Per source and observation point: connection rate, destination-host/port fan-out, response/failure ratio and previously unseen destinations. Compare equivalent time windows; separate authorized scanners, NAT and sampling effects.
  1. Define an entity/peer group and feature; exclude the evaluation period from baseline training.
  2. Use representative normal and maintenance activity. Do not invent a production threshold from a synthetic example.
  3. Evaluate held-out behavior-positive and benign cases; measure false positives, misses and telemetry loss separately.
  4. Keep abnormality separate from maliciousness. Correlate with the behavior-specific source evidence.

Anomaly Detection Atlas · Baseline, validation and blind spots

Attack tools and documented software

No reviewed lab-tool association is selected for this exact technique. This is a curation gap, not a statement that no tool can implement the behavior.

Software observed in source procedures

These are exact ATT&CK software-use relationships, including malware. They provide behavior context, not recommendations to download or execute malware. No safety or detector claim is inherited.

3 source-documented software associations

Simulation design and documented procedures

Atomic evidence: no compatible candidate in this snapshot. Live lab status: not run for these imported procedures.

Use a process simulator or isolated test rig with no connection to production controllers or physical actuators. Preserve safety interlocks; destructive effects require synthetic evidence, not real equipment damage.

No compatible Atomic procedure is present in this pinned evidence set. Technical feasibility has not been ruled out. A custom procedure must define the behavior, target, collection point, success observable and rollback before execution.

Technique-specific experiment contract

  1. Choose one procedure implementing T0885 Commonly Used Port; identify the observable behavior in the source definition, not just its tactic.
  2. Record exact target, tool/version, inputs, privileges, network limits and approval. Never run an imported default target automatically.
  3. Enable the collection sources above and verify a benign baseline reaches the detector.
  4. Run only the approved isolated scenario; capture native events and an independent behavior observable.
  5. Evaluate the exact rule/model, restore the lab, and preserve configuration, event hashes, alerts, controls and misses.

Synthetic logs and offline contract check

Download synthetic collection fixture (JSON) · Download the complete engineering workbook

This fixture exercises the listed collection fields. It does not reproduce Commonly Used Port, label its example events as malicious, or measure detection effectiveness. Use the exact analytic and selected procedure to build an independently labelled behavior-positive dataset.

Not run in this browser. No network scan or attack command is executed by this control.

Validation status and remaining work

Source identity
Joined by exact technique/object IDs against hash-pinned sources.
Collection fixture
Available for offline schema exercises; not attack emulation.
Native telemetry / backend / real attack
Not validated for these imported procedures. Source fidelity and page tests cannot establish sensor or detector effectiveness.

All-page audit and evidence inventory · This page’s machine-readable workbook

Sources and evidence boundaries

Pinned MITRE STIX source · SHA-256 c9ca0ce523a1b5e512060a390415e8aefe8f6d32c5f82d7de81264960c1e1183. Definition and procedure context are reproduced from this snapshot, not independently re-investigated incidents.

Source-linked mitigations
  • M0804 Human User Authentication

    All field controllers should require users to authenticate for all remote or local management sessions. The authentication mechanisms should also support Account Use Policies, Password Policies, and User Account Management.

  • M0930 Network Segmentation

    Configure internal and external firewalls to block traffic using common ports that associate to network protocols that may be unnecessary for that particular network segment.

  • M0931 Network Intrusion Prevention

    Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level. Signatures are often for unique indicators within protocols and may be based on the specific protocol used by a particular adversary or tool and will likely be different across various malware families and versions. Adversaries will likely change tool C2 signatures over time or construct protocols in such a way as to avoid detection by common defensive tools.[University of Birmingham C2]

  • M0942 Disable or Remove Feature or Program

    Ensure that unnecessary ports and services are closed to prevent risk of discovery and potential exploitation.

Connected ecosystem references

Linked tags

Detection and collection

T0885 detection workspace

No reviewed association in this snapshot.

Pinned research references. No browser attack runner or production-validated detector is asserted. Imported procedures remain unvalidated; any bounded lab evidence has its own scope. ATT&CK / Atomic provenance · Detection provenance.