12 lines
2.4 KiB
Markdown
12 lines
2.4 KiB
Markdown
# Native transfer type controls
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`fileTransfers.upload` and `fileTransfers.download` independently configure `maxBytes`, `allowTypes`, `blockedTypes`, `blockUnknown`, `blockExtensionMismatch`, `blockMimeMismatch`, and `allowWithoutMalwareScanner` in the signed managed policy. Types are `pe`, `elf`, `macho`, `pdf`, `zip`, `png`, `jpeg`, `gif`, `webp`, `gzip`, `text`, and `unknown`. A blocked type always takes precedence over an allowlist. Empty allowlists do not restrict types. Unknown and mismatch blocks are explicit options to accommodate enterprise compatibility requirements.
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Classification reads actual bounded bytes, never trusts the filename or declared MIME type. Text recognition checks the entire UTF-8 payload for binary control bytes. MZ-family files are identified even if their PE headers are truncated. ZIP and Office OOXML share a container signature; this classifier does not distinguish document subtypes, recursively inspect archive members, prove a media decoder accepts the file, or detect every polyglot. Document extraction, YARA and ICAP remain separate inspection layers. A magic allow verdict is not a security verdict.
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Downloads classify the complete bounded memory buffer before antivirus inspection, file-picker display or destination write. Their released digest remains bound to the exact scanned bytes. Supported document/media signatures additionally require complete contained local DLP extraction; semantic scanning applies when configured. Executable and unknown content may have antivirus coverage without document extraction coverage; configure blocked types or `blockUnknown` for stricter profiles.
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Each enabled malware scanner remains mandatory. YARA can be disabled independently while selected-channel ICAP is enabled. Disabling both does not silently bypass the download gate: an administrator must explicitly set `allowWithoutMalwareScanner: true`, and complete local DLP is still mandatory. This flag cannot override an enabled scanner's outage or failure.
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The helper returns sanitized filename, claimed MIME, detected type, byte count and SHA-256 for protected evidence. Ordinary download audit events carry only bounded byte count, detected type and SHA-256. Native file/data-pipe upload release remains blocked until immutable scanning and transport binding can be proved. Classification of a multipart request envelope does not prove classification of its individual attachments.
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