Archive extraction preflight: zip-slip, duplicate destinations, symlink conflicts

$0.005 USDC per call · Developer and security · POST /api/v1/archive-preflight · Id archive-preflight

Checks a manifest of up to 2000 archive entries (path, type, link target, sizes) before extraction, for an agent that unpacks zip, tar or OOXML files: ../ traversal (also through backslashes), absolute, drive-letter and UNC paths, entries that write through a symlink, symlink and hardlink targets that leave the root, duplicate destinations, case-only and NFC/NFD collisions, Windows reserved names, and declared-size limits. It reads only the manifest you supply: it does not open or decompress the archive, check file contents, or know the extractor's own sanitising, so a pass means the manifest has no listed hazard.

What you get

Zip-slip and symlink write-through are how an archive overwrites files outside the target folder. The check runs on the file list before anything is written.

Call it

Send the JSON body below to https://agents.writerslogic.com/api/v1/archive-preflight. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.

curl -i -X POST https://agents.writerslogic.com/api/v1/archive-preflight \
  -H 'content-type: application/json' \
  -d '{"entries":[{"path":"app/","type":"dir"},{"path":"app/run.sh","type":"file","size":120},{"path":"app/Run.sh","type":"file","size":90},{"path":"app/link","type":"symlink","linkTarget":"../../etc"},{"path":"app/link/passwd","type":"file","size":5},{"path":"..\\..\\evil.dll","type":"file","size":1}]}'

Input

Field	Type	Required	Description
`entries`	array<object>; max 2000 items	yes	At most 200000 characters of paths and link targets in total.
`targets`	array<string; one of "windows", "macos", "linux">; max 3 items	no	Filesystems to check collisions and name rules for. Default: windows, macos and linux.
`destinationRoot`	string; length 0..1024	no	Extraction directory; counted towards total path length.
`limits`	object	no

Example request body

{
  "entries": [
    {
      "path": "app/",
      "type": "dir"
    },
    {
      "path": "app/run.sh",
      "type": "file",
      "size": 120
    },
    {
      "path": "app/Run.sh",
      "type": "file",
      "size": 90
    },
    {
      "path": "app/link",
      "type": "symlink",
      "linkTarget": "../../etc"
    },
    {
      "path": "app/link/passwd",
      "type": "file",
      "size": 5
    },
    {
      "path": "..\\..\\evil.dll",
      "type": "file",
      "size": 1
    }
  ]
}

Result

The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.

Field	Type	Required	Description
`status`	string; one of "pass", "fail", "unknown", "unsupported"	no	pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.
`checked`	integer	no
`targets`	array<string>	no
`findings`	array<object>	no	Capped at 100. Errors make the status fail; warnings do not.
`findingCount`	integer	no
`witnesses`	array<object>	no
`versions`	object	no	Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
`limits`	array<string>	no
`deterministic`	boolean	no	Always true: pure code, no model.

Pay and connect

Available through: x402 (USDC on Base), MCP. MCP clients reach it through the infra-preflight-kit package.

Machine-readable

This agent as JSON (schemas, example, OpenAPI operation)
Free signed sample response
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