47 lines
3.1 KiB
Markdown
47 lines
3.1 KiB
Markdown
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# Outgoing header DLP
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The managed browser intercepts final outgoing HTTP headers in its privileged
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session `onBeforeSendHeaders` listener. This stage runs before HTTP data is sent,
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according to the [Electron WebRequest contract](https://www.electronjs.org/docs/latest/api/web-request#webrequestonbeforesendheadersfilter-listener).
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It supplements the existing URL, body, DNS and destination gates.
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Chromium may already have opened a TCP connection before this callback; the
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guarantee concerns release of HTTP data, not preventing a connection attempt.
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All fields are inspected, including custom headers, Cookie, Authorization,
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Proxy-Authorization and Referer. There is no credential-field exemption. Ordinary
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opaque session cookies, Basic credentials and JWT bearer strings remain usable
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unless they match a central rule. Recognizable `sk-` or GitHub API tokens match
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the existing generic secret detector even when used as direct API credentials;
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approved AI integrations should use the controlled gateway.
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The browser copies and validates at most 128 fields and 64 KiB, bounded further
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by the signed DLP byte limit. Invalid fields, inaccessible snapshots and scanner
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failures block. Each value is scanned separately for exact document fingerprints;
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joined values catch literals split across fields; the serialized complete snapshot
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is also inspected. Existing core percent decoding and phrase normalization apply.
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This is not a claim of decoding arbitrary compression, encryption or encodings.
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Signed-policy semantic and YARA inspection runs locally on the complete header
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snapshot when enabled. An enabled upload ICAP connector also inspects this snapshot,
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including credential fields: administrators must treat the configured company
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scanner as trusted infrastructure. Scanners require a complete allow result.
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Revocation, expiry, policy replacement, source navigation or the 40-second deadline
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prevent release. Chromium receives the exact frozen snapshot approved by the gate.
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Mutable byte buffers are wiped after inspection; JavaScript string copies are
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garbage-collected and cannot be reliably overwritten.
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Ordinary audit receives only the existing rule ID and destination hostname on
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block. `browser.request.headers` exports field count, byte count, timing and request
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type under a `browser.request` parent. Header values, names, token hashes and cookie
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contents are not added to security audit or diagnostic traces.
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The native deadline cancels exactly once and records the static
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`headers-inspection-timeout` reason. A late scanner approval cannot release the
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request, and a failed audit write cannot turn the cancellation into an allow.
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This covers the final header fields exposed by Electron for the managed session.
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For WebSockets, this stage inspects handshake headers only; it does not inspect
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subsequent frames. WebSockets remain disabled by the baseline policy, and a
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delegated exception does not establish full frame-level DLP coverage.
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It does not establish protection against arbitrary transformed covert channels,
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other OS applications or every network layer generated internally by Chromium.
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Native receiver tests must prove prohibited requests never reach their destination.
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