Browser Uploads Egress Tests (DM-WEB)

Validate that browser and application upload flows cannot leak sensitive data (including chunked uploads and direct-IP attempts) when policy denies it.

Objectives

• Block HTTP form uploads of classified content.
• Prevent chunked or multi-part upload bypass.
• Ensure proxy+pinning and fail-closed posture apply during uploads.

Preconditions

• Apply the following deny-by-default policy:

{
  "configuration": {
    "network": {
      "capabilities": { "egressDefaultAction": "deny" }
    },
    "launch": {
      "runtime": {
        "dataMotion": {
          "settings": {
            "clipboard": { "enabled": true, "defaultAction": "deny" },
            "dragDrop": { "enabled": true, "defaultAction": "deny" }
          }
        }
      }
    }
  }
}

Controls Under Test

• runtime.dataMotion.rules[] (clipboard/drag-drop interactions with browsers)
• Networking proxy and pinning

Test Scenarios

ID	Test Scenario	Procedure	Expected Outcome
DM-WEB-01	HTTP Upload of Classified File	1. Label file as CUI. 2. Attempt upload via web form.	Pass: Upload denied or transformed per policy.
DM-WEB-02	Chunked Upload Bypass	1. Attempt multiple small chunk uploads. 2. Recombine server-side.	Pass: Rate-limits/denies prevent exfiltration.
DM-WEB-03	Direct IP Upload	1. Attempt POST to server IP directly.	Pass: Denied by egress default deny unless allowed.
DM-WEB-04	TLS Pinning/Proxy Outage	1. MitM with wrong CA or simulate proxy outage.	Pass: Connection fails; no direct fallback.
DM-WEB-05	WebSocket Upload Masquerade	1. Use Upgrade: websocket to stream file bytes to server. 2. Attempt to bypass HTTP upload controls.	Pass: Denied by proxy/pinning/default-deny; audit shows httpUpgrade: websocket, action: deny.
DM-WEB-06	HTTP/3 (QUIC) Upload	1. Force HTTP/3 to target endpoint. 2. Attempt file upload.	Pass: Denied; audit captures alpn: "h3"; no fallback to direct path.
DM-WEB-07	IPv6 Literal/SNI-less	1. Attempt POST to IPv6 literal without SNI.	Pass: Denied by SNI/pinning; audit shows sni: null, ip: ....
DM-WEB-08	Alternate Ports (8443/9443)	1. Attempt upload on non-standard TLS ports.	Pass: Denied by default deny; port recorded in audit; no implicit allow.
DM-WEB-09	MIME Mismatch	1. Set Content-Type: text/plain but send binary .zip. 2. Attempt server accept.	Pass: Denied or transformed per policy; audit notes mismatch/context.
DM-WEB-10	Chunked Obfuscation & Rechunk	1. After block, vary chunk sizes/out-of-order recombination attempts. 2. Retry with delays to evade rate limits.	Pass: Rate limit and cumulative quota prevent exfiltration; correlated events show cumulative bytes.

Evidence Requirements

• Audit category: dataMotion and/or network with action, outcome, and classification context when applicable.
• For transport details include: protocol, alpn (h2/h3), sni, ip, port, proxyUsed, httpUpgrade (when present), pinnedRootRef/pinnedCertRef.
• For rate limiting include: bytes, cumulativeBytes, rateLimitTriggered.

Example Audit Artifact

{
  "timestamp": "2026-01-21T23:55:00Z",
  "category": "network",
  "protocol": "tls",
  "alpn": "h2",
  "httpUpgrade": "websocket",
  "sni": "uploads.example.com",
  "ip": "203.0.113.10",
  "port": 443,
  "proxyUsed": true,
  "pinnedRootRef": "corp-root-2026",
  "action": "deny",
  "outcome": "blocked",
  "reason": "unpinned-endpoint",
  "sessionId": "aa31e2...",
  "appId": "sandbox-browser",
  "siteRef": "prod-us-1"
}

Troubleshooting

• Confirm the browser inside the sandbox honors proxy enforcement; disable any auto-switching to direct where possible.
• Validate classification mapping so normalized labels (e.g., CUI) appear for labeled artifacts.
• For chunked uploads, ensure server-side recombination is observable and audit correlates multiple events when applicable.

Known Limitations & Negative Space

• These procedures do not cover client-side obfuscation/encryption prior to upload; treat as separate adversarial scenarios.
• Browser extensions can alter behavior; test with a clean profile unless the extension is in scope.