T1033 — System Owner/User Discovery

# T1033 - System Owner/User Discovery

## SOC Recommendation
Investigate System Owner/User Discovery activity in the context of Discovery: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.

## D3FEND Mappings
| D3FEND Technique | Relationship | Practical SOC Action |
|---|---|---|
| File Analysis | Detect | Monitor for File Analysis indicators relevant to this technique. |
| File Encryption | Harden | Apply File Encryption to reduce this technique's viability before an incident occurs. |
| File Eviction | Evict | Use File Eviction to remove the adversary's foothold once this technique is confirmed. |
| Content Filtering | Isolate | Apply Content Filtering to contain the blast radius once this technique is observed. |

## Investigation Steps
1. Review Defender for Endpoint / Defender XDR alerts and timeline for the affected host or identity.
2. Check Sentinel analytics rules and incidents correlated with this technique.
3. Review Entra ID sign-in and audit logs if the technique involves an identity or cloud resource.

## Evidence to Collect
- Host or resource affected
- Account or identity involved
- Timestamp of the activity
- Related process, file, or network artifact
- Any preceding or follow-on alerts

## Response Actions
| Action | Risk | Automation Safe | Approval Required |
|---|---|---|---|
| Contain the affected host or account | Medium | No | Yes |
| Collect and preserve evidence | Low | Yes | No |

## KQL
```kql
DeviceEvents
| where TimeGenerated > ago(24h)
| where ActionType has "<tune to T1033>"
```

## Escalation Criteria
- System Owner/User Discovery activity observed on a privileged account or critical system.
- Activity follows or precedes other suspicious behaviour in the same investigation.
- Automated triage cannot confidently rule out malicious intent.

## False Positive Considerations
- Legitimate administrative or maintenance activity matching this pattern.
- Approved security testing or red team exercise.
- Known benign software producing similar telemetry.

Generated by SOC Response Atlas by Basyrix.

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• /api/techniques/T1033.json
• /api/recommendations/T1033.json
• /api/d3fend/T1033.json
• /api/mappings/T1033.json
• /api/confluence/T1033.md

Example curl:

curl https://atlas.basyrix.com/api/recommendations/T1033.json

Response:

{
  "technique_id": "T1033",
  "name": "System Owner/User Discovery",
  "priority": "high",
  "status": "draft",
  "version": "0.1.0",
  "last_reviewed": "2026-07-23",
  "generated_by": "SOC Response Atlas by Basyrix",
  "tactics": [
    "Discovery"
  ],
  "platforms": [
    "Linux",
    "macOS",
    "Network Devices",
    "Windows"
  ],
  "summary": "Adversaries may attempt to identify the primary user, currently logged in user, set of users that commonly uses a system, or whether a user is actively using the system. They may do this, for example, by retrieving account usernames or by using [OS Credential Dumping](https://attack.mitre.org/techniques/T1003)...",
  "soc_recommendation": "Investigate System Owner/User Discovery activity in the context of Discovery: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.",
  "d3fend_mappings": [
    {
      "id": "D3-FA",
      "name": "File Analysis",
      "relationship": "detect",
      "practical_action": "Monitor for File Analysis indicators relevant to this technique.",
      "tooling": [
        "Defender for Endpoint"
      ]
    },
    {
      "id": "D3-FE",
      "name": "File Encryption",
      "relationship": "harden",
      "practical_action": "Apply File Encryption to reduce this technique's viability before an incident occurs.",
      "tooling": [
        "Defender for Endpoint"
      ]
    },
    {
      "id": "D3-FEV",
      "name": "File Eviction",
      "relationship": "evict",
      "practical_action": "Use File Eviction to remove the adversary's foothold once this technique is confirmed.",
      "tooling": [
        "Defender for Endpoint"
      ]
    },
    {
      "id": "D3-CF",
      "name": "Content Filtering",
      "relationship": "isolate",
      "practical_action": "Apply Content Filtering to contain the blast radius once this technique is observed.",
      "tooling": [
        "Defender for Endpoint"
      ]
    }
  ],
  "investigation_steps": {
    "microsoft": [
      "Review Defender for Endpoint / Defender XDR alerts and timeline for the affected host or identity.",
      "Check Sentinel analytics rules and incidents correlated with this technique.",
      "Review Entra ID sign-in and audit logs if the technique involves an identity or cloud resource."
    ],
    "generic": [
      "Confirm whether the observed system owner/user discovery activity matches expected administrative or application behaviour.",
      "Identify the host, account, or resource where the activity occurred and its business criticality.",
      "Check for related alerts before and after this activity to reconstruct the broader intrusion timeline.",
      "Real detection reference: \"Suspicious React Server Child Process\" -- This rule detects suspicious child process activity from a React server application. This could be related to successful exploitation of CVE-2025-55182 or CVE-2025-66478..."
    ]
  },
  "evidence_to_collect": [
    "Host or resource affected",
    "Account or identity involved",
    "Timestamp of the activity",
    "Related process, file, or network artifact",
    "Any preceding or follow-on alerts"
  ],
  "response_actions": [
    {
      "name": "Contain the affected host or account",
      "category": "Containment",
      "risk": "Medium",
      "automation_safe": false,
      "approval_required": true,
      "tool": "Defender for Endpoint / Entra ID",
      "notes": "Requires approval -- confirm malicious intent before isolating a host or disabling an account."
    },
    {
      "name": "Collect and preserve evidence",
      "category": "Investigation",
      "risk": "Low",
      "automation_safe": true,
      "approval_required": false,
      "tool": "Defender for Endpoint",
      "notes": "Safe -- read-only evidence collection."
    }
  ],
  "queries": {
    "kql": [
      {
        "name": "Starting point for T1033",
        "description": "Generic starting query -- tune to the specific data source relevant to this technique.",
        "query": "DeviceEvents\n| where TimeGenerated > ago(24h)\n| where ActionType has \"<tune to T1033>\""
      }
    ],
    "spl": [],
    "esql": [
      {
        "name": "ae3e9625-89ad-4fc3-a7bf-fced5e64f01b — Suspicious React Server Child Process",
        "description": "(EQL) This rule detects suspicious child process activity from a React server application. This could be related to successful exploitation of CVE-2025-55182 or CVE-2025-66478... (Source: Elastic's official detection-rules repository (Elastic License v2).)",
        "query": "process where event.type == \"start\" and event.action in (\"exec\", \"executed\", \"start\", \"process_started\") and (\n    process.name in (\n      \"sh\", \"bash\", \"zsh\", \"dash\", \"curl\", \"wget\", \"id\", \"whoami\", \"uname\", \"cmd.exe\", \"cat\", \"powershell.exe\", \"java\", \"rundll32.exe\", \"wget.exe\", \"certutil.exe\",\n      \"nc\", \"ncat\", \"netcat\", \"nc.openbsd\", \"nc.traditional\", \"socat\", \"busybox\", \"mkfifo\", \"nohup\", \"setsid\", \"xterm\"\n    ) or\n    (process.name : \"python*\" and process.args : \"-c\" and process.args : (\n     \"*import*pty*spawn*\", \"*import*subprocess*call*\"\n    )) or\n    (process.name : \"perl*\" and process.args : \"-e\" and process.args : \"*socket*\" and process.args : (\n     \"*exec*\", \"*system*\"\n    )) or\n    (process.name : \"ruby*\" and process.args : (\"-e\", \"-rsocket\") and process.args : (\n     \"*TCPSocket.new*\", \"*TCPSocket.open*\"\n     )) or\n    (process.name : \"lua*\" and process.args : \"-e\" and process.args : \"*socket.tcp*\" and process.args : (\n     \"*io.popen*\", \"*os.execute*\"\n    )) or\n    (process.name : \"php*\" and process.args : \"-r\" and process.args : \"*fsockopen*\" and process.args : \"*/bin/*sh*\") or \n    (process.name == \"node\" and process.args == \"-e\" and process.args : \"*spawn*sh*\" and process.args : \"*connect*\") or\n    (process.name : (\"awk\", \"gawk\", \"mawk\", \"nawk\") and process.args : \"*/inet/tcp/*\") or\n    (process.name in (\"rvim\", \"vim\", \"vimdiff\", \"rview\", \"view\") and process.args == \"-c\" and process.args : \"*socket*\")\n)\nand (\n  ?process.working_directory : (\n    \"*react-dom*\", \"*.next*\", \"*node_modules/next*\", \"*react-server*\", \"*bin/next*\", \"*.pnpm/next*\", \"*next/dist/server*\", \"*react-scripts*\") or\n  (\n    process.parent.name in (\"node\", \"bun\", \"node.exe\", \"bun.exe\") and\n    process.parent.command_line : (\n      \"*react-dom*\", \"*.next*\", \"*node_modules/next*\", \"*react-server*\", \"*next-server*\", \"* server.js*\",  \"*start-server.js*\", \"*bin/next*\",\n      \"*--experimental-https*\", \"*app/server*\", \"*.pnpm/next*\", \"*next start*\", \"*next dev*\", \"*react-scripts start*\", \"*next/dist/server*\"\n    )\n  )\n) and not (\n  ?process.parent.executable in (\"./runc\", \"/opt/google/chrome/chrome\") or\n  process.command_line like \"/bin/sh -c git config*\"\n)"
      },
      {
        "name": "e0cc3807-e108-483c-bf66-5a4fbe0d7e89 — Potentially Suspicious Process Started via tmux or screen",
        "description": "(EQL) This rule monitors for the execution of suspicious commands via screen and tmux. When launching a command and detaching directly, the commands will be executed in the background via its parent process. Attackers may leverage screen or tmux to execute commands while attempting to evade detection. (Source: Elastic's official detection-rules repository (Elastic License v2).)",
        "query": "process where host.os.type == \"linux\" and event.type == \"start\" and\n  event.action in (\"exec\", \"exec_event\", \"start\", \"ProcessRollup2\") and\n  process.parent.name in (\"screen\", \"tmux\") and process.name like (\n    \"nmap\", \"nc\", \"ncat\", \"netcat\", \"socat\", \"nc.openbsd\", \"ngrok\", \"ping\", \"java\", \"php*\", \"perl\", \"ruby\", \"lua*\",\n    \"openssl\", \"telnet\", \"wget\", \"curl\", \"id\"\n  )"
      }
    ]
  },
  "automation": {
    "safe": [
      "Add recommendation as Sentinel incident comment.",
      "Run enrichment queries.",
      "Create ServiceNow SecOps task."
    ],
    "approval_required": [
      "Contain or disable the affected host/account.",
      "Any change to production configuration."
    ]
  },
  "escalation_criteria": [
    "System Owner/User Discovery activity observed on a privileged account or critical system.",
    "Activity follows or precedes other suspicious behaviour in the same investigation.",
    "Automated triage cannot confidently rule out malicious intent."
  ],
  "false_positive_considerations": [
    "Legitimate administrative or maintenance activity matching this pattern.",
    "Approved security testing or red team exercise.",
    "Known benign software producing similar telemetry."
  ],
  "confluence": {
    "title": "T1033 - System Owner/User Discovery Response Guidance",
    "labels": [
      "mitre",
      "attack",
      "d3fend",
      "secops",
      "basyrix"
    ],
    "sections": [
      "summary",
      "d3fend_mappings",
      "investigation_steps",
      "response_actions",
      "queries",
      "automation",
      "escalation_criteria",
      "false_positive_considerations"
    ]
  }
}