T1537 — Transfer Data to Cloud Account

# T1537 - Transfer Data to Cloud Account

## SOC Recommendation
Investigate Transfer Data to Cloud Account activity in the context of Exfiltration: 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 |
|---|---|---|
| Network Traffic Analysis | Detect | Monitor for Network Traffic Analysis indicators relevant to this technique. |

## 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 |
|---|---|---|---|
| Block personal cloud storage services at network egress (pro | Medium | No | Yes |
| Suspend account access | Low | No | Yes |
| Notify HR and Legal — preserve evidence for proceedings | Low | Yes | No |
| Assess data sensitivity and breach notification obligations | Low | No | Yes |

## KQL
```kql
let PersonalCloud = dynamic([
    "dropbox.com", "dropboxapi.com", "content.dropboxapi.com",
    "drive.google.com",
    "mega.nz", "mega.co.nz",
    "wetransfer.com", "we.tl",
    "box.com", "upload.box.com",
    "onedrive.live.com", "storage.live.com",
    "mediafire.com", "sendspace.com", "gofile.io",
    "file.io", "transfer.sh", "anonfiles.com",
    "raw.githubusercontent.com", "gist.github.com", "paste.ee", "pastebin.com"
]);
DeviceNetworkEvents
| where TimeGenerated >= ago(1h)
| where RemoteUrl has_any (PersonalCloud)
| summarize
    Sessions = count(),
    DestDomains = make_set(RemoteUrl, 5)
    by DeviceName, InitiatingProcessFileName
| where Sessions > 10
| extend timestamp = now(), HostCustomEntity = DeviceName
| order by Sessions desc
```
```kql
// High severity - Social and Public Exposure - Exposure of PII/CII in Public Domain
let timeFrame = 5m;
CyfirmaSPEPIIAndCIIAlerts_CL
| where severity == 'Critical' and TimeGenerated between (ago(timeFrame) .. now())
| extend
    Description=description,
    FirstSeen=first_seen,
    LastSeen=last_seen,
    RiskScore=risk_score,
    AlertUID=alert_uid,
    UID=uid,
    AssetType=asset_type,
    AssetValue=signature,
    Source=source,
    Impact=impact,
    Recommendation=recommendation,
    PostedDate=posted_date,
    ProviderName='CYFIRMA',
    ProductName='DeCYFIR/DeTCT',
    AlertTitle=Alert_title
| project
    TimeGenerated,
    Description,
    RiskScore,
    FirstSeen,
    LastSeen,
    AlertUID,
    UID,
    AssetType,
    AssetValue,
    Source,
    Impact,
    Recommendation,
    PostedDate,
    ProductName,
    ProviderName,
    AlertTitle
```
```kql
TheomAlerts_CL
 | where priority_s == "P1"
```

## Escalation Criteria
- Transfer Data to Cloud Account 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/T1537.json
• /api/recommendations/T1537.json
• /api/d3fend/T1537.json
• /api/mappings/T1537.json
• /api/confluence/T1537.md

Example curl:

curl https://atlas.basyrix.com/api/recommendations/T1537.json

Response:

{
  "technique_id": "T1537",
  "name": "Transfer Data to Cloud Account",
  "priority": "high",
  "status": "complete",
  "version": "0.1.0",
  "last_reviewed": "2026-07-23",
  "generated_by": "SOC Response Atlas by Basyrix",
  "tactics": [
    "Exfiltration"
  ],
  "platforms": [
    "IaaS",
    "Office Suite",
    "SaaS"
  ],
  "summary": "Adversaries may exfiltrate data by transferring the data, including through sharing/syncing and creating backups of cloud environments, to another cloud account they control on the same service. A defender who is monitoring for large transfers to outside the cloud environment through normal file transfers or over command and control channels may not be watching for data transfers to another account within the same cloud provider...",
  "soc_recommendation": "Investigate Transfer Data to Cloud Account activity in the context of Exfiltration: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.",
  "d3fend_mappings": [
    {
      "id": "D3-NTA",
      "name": "Network Traffic Analysis",
      "relationship": "detect",
      "practical_action": "Monitor for Network Traffic Analysis indicators relevant to this technique.",
      "tooling": [
        "Sentinel",
        "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 transfer data to cloud account 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: \"Transfer to Personal Cloud Storage\" -- Flags significant data uploads to personal or unapproved cloud storage services (Dropbox, Google Drive, WeTransfer, Mega, Box, personal OneDrive, pastebin, etc.) - the most common exfiltration method for insider threats."
    ]
  },
  "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": "Block personal cloud storage services at network egress (pro",
      "category": "Response",
      "risk": "Medium",
      "automation_safe": false,
      "approval_required": true,
      "tool": "See investigation guide",
      "notes": "Block personal cloud storage services at network egress (proxy/firewall)"
    },
    {
      "name": "Suspend account access",
      "category": "Response",
      "risk": "Low",
      "automation_safe": false,
      "approval_required": true,
      "tool": "See investigation guide"
    },
    {
      "name": "Notify HR and Legal — preserve evidence for proceedings",
      "category": "Response",
      "risk": "Low",
      "automation_safe": true,
      "approval_required": false,
      "tool": "See investigation guide"
    },
    {
      "name": "Assess data sensitivity and breach notification obligations",
      "category": "Response",
      "risk": "Low",
      "automation_safe": false,
      "approval_required": true,
      "tool": "See investigation guide"
    }
  ],
  "queries": {
    "kql": [
      {
        "name": "GEN-EF-003 — Transfer to Personal Cloud Storage",
        "description": "Flags significant data uploads to personal or unapproved cloud storage services (Dropbox, Google Drive, WeTransfer, Mega, Box, personal OneDrive, pastebin, etc.) - the most common exfiltration method for insider threats. (Source: Bell Integration baseline detection library.)",
        "query": "let PersonalCloud = dynamic([\n    \"dropbox.com\", \"dropboxapi.com\", \"content.dropboxapi.com\",\n    \"drive.google.com\",\n    \"mega.nz\", \"mega.co.nz\",\n    \"wetransfer.com\", \"we.tl\",\n    \"box.com\", \"upload.box.com\",\n    \"onedrive.live.com\", \"storage.live.com\",\n    \"mediafire.com\", \"sendspace.com\", \"gofile.io\",\n    \"file.io\", \"transfer.sh\", \"anonfiles.com\",\n    \"raw.githubusercontent.com\", \"gist.github.com\", \"paste.ee\", \"pastebin.com\"\n]);\nDeviceNetworkEvents\n| where TimeGenerated >= ago(1h)\n| where RemoteUrl has_any (PersonalCloud)\n| summarize\n    Sessions = count(),\n    DestDomains = make_set(RemoteUrl, 5)\n    by DeviceName, InitiatingProcessFileName\n| where Sessions > 10\n| extend timestamp = now(), HostCustomEntity = DeviceName\n| order by Sessions desc"
      },
      {
        "name": "52d71822-41e4-4c21-b36f-400294f2b43a — CYFIRMA - Social and Public Exposure - Exposure of PII/CII in Public Domain Rule",
        "description": "\"This analytics rule detects high severity alerts from CYFIRMA indicating exposure of Personally Identifiable Information (PII) or Confidential Information (CII) in public or unsecured sources. Such leaks may include email addresses, credentials, phone numbers, or other sensitive personal or organizational data. These exposures can lead to identity theft, phishing, credential compromise, or regulatory non-compliance. Investigate promptly and initiate remediation steps including user notifications and credential resets.\" (Source: Microsoft's official Azure-Sentinel Detections (MIT licensed).)",
        "query": "// High severity - Social and Public Exposure - Exposure of PII/CII in Public Domain\nlet timeFrame = 5m;\nCyfirmaSPEPIIAndCIIAlerts_CL\n| where severity == 'Critical' and TimeGenerated between (ago(timeFrame) .. now())\n| extend\n    Description=description,\n    FirstSeen=first_seen,\n    LastSeen=last_seen,\n    RiskScore=risk_score,\n    AlertUID=alert_uid,\n    UID=uid,\n    AssetType=asset_type,\n    AssetValue=signature,\n    Source=source,\n    Impact=impact,\n    Recommendation=recommendation,\n    PostedDate=posted_date,\n    ProviderName='CYFIRMA',\n    ProductName='DeCYFIR/DeTCT',\n    AlertTitle=Alert_title\n| project\n    TimeGenerated,\n    Description,\n    RiskScore,\n    FirstSeen,\n    LastSeen,\n    AlertUID,\n    UID,\n    AssetType,\n    AssetValue,\n    Source,\n    Impact,\n    Recommendation,\n    PostedDate,\n    ProductName,\n    ProviderName,\n    AlertTitle"
      },
      {
        "name": "bb9051ef-0e72-4758-a143-80c25ee452f0 — Theom Critical Risks",
        "description": "\"Creates Microsoft Sentinel incidents for critical risk Theom alerts.\" (Source: Microsoft's official Azure-Sentinel Detections (MIT licensed).)",
        "query": "TheomAlerts_CL\n | where priority_s == \"P1\""
      }
    ],
    "spl": [],
    "esql": [
      {
        "name": "699fdfb9-8430-4dcb-b5a9-da67dae64808 — AWS ECR Repository or Registry Policy Granted Public Access",
        "description": "(ESQL) Detects when an Amazon ECR repository or registry policy is modified to grant public access using a wildcard principal (Principal:\"*\") statement... (Source: Elastic's official detection-rules repository (Elastic License v2).)",
        "query": "FROM logs-aws.cloudtrail-* METADATA _id, _version, _index\n| WHERE event.provider == \"ecr.amazonaws.com\"\n  AND event.action IN (\"SetRepositoryPolicy\", \"PutRegistryPolicy\")\n  AND event.outcome == \"success\"\n  AND (aws.cloudtrail.user_identity.type IS NULL OR aws.cloudtrail.user_identity.type != \"AWSService\")\n  AND aws.cloudtrail.request_parameters RLIKE \"\"\".*\\\"Effect\\\": *\\\"Allow\\\".*\"\"\"\n  AND (aws.cloudtrail.request_parameters RLIKE \"\"\".*\\\"Principal\\\": *\\\"\\*\\\".*\"\"\"\n       OR aws.cloudtrail.request_parameters RLIKE \"\"\".*\\\"Principal\\\": *\\{ *\\\"AWS\\\": *\\\"\\*\\\".*\"\"\")\n| KEEP _id, _version, _index, @timestamp, aws.*, cloud.*, event.*, source.*, user.*, user_agent.*"
      },
      {
        "name": "d488f026-7907-4f56-ad51-742feb3db01c — AWS S3 Bucket Replicated to Another Account",
        "description": "(EQL) Identifies the creation or modification of an S3 bucket replication configuration that sends data to a bucket in a different AWS account... (Source: Elastic's official detection-rules repository (Elastic License v2).)",
        "query": "info where data_stream.dataset == \"aws.cloudtrail\"\n   and event.action == \"PutBucketReplication\"\n   and event.outcome == \"success\"\n   and stringContains(aws.cloudtrail.request_parameters, \"Account=\")"
      }
    ]
  },
  "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": [
    "Transfer Data to Cloud Account 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": "T1537 - Transfer Data to Cloud Account Response Guidance",
    "labels": [
      "mitre",
      "attack",
      "d3fend",
      "secops",
      "basyrix"
    ],
    "sections": [
      "summary",
      "d3fend_mappings",
      "investigation_steps",
      "response_actions",
      "queries",
      "automation",
      "escalation_criteria",
      "false_positive_considerations"
    ]
  }
}