npm · apostrophe
ApostropheCMS: Unauthenticated resource exhaustion via pre-auth aposBigUpload processing in @apostrophecms/import-export
A potential unauthenticated denial-of-service vulnerability exists in the chunked import upload path used by @apostrophecms/import-export.
The affected import API routes invoke:
self.apos.http.bigUploadMiddleware()
before the actual import handler performs its authentication check.
Because no authorize callback is supplied to bigUploadMiddleware(), unauthenticated requests can reach the aposBigUpload start, chunk, and end operations before the later req.user check rejects the import.
As a result, an unauthenticated remote attacker can create server-side upload state, write chunk data to upload storage, trigger temporary-file processing, and cause attacker-controlled cleanup operations before authentication is enforced.
Package:
@apostrophecms/import-export
Confirmed affected version:
3.6.2
Potential earlier affected versions:
The issue may affect earlier 3.x releases in which the current big-upload-based import implementation is present. I have not yet fully verified the exact introduction version and recommend that the maintainers confirm the affected version range.
Primary:
CWE-400 — Uncontrolled Resource Consumption
Related:
CWE-306 — Missing Authentication for Critical Function
CWE-770 — Allocation of Resources Without Limits or Throttling
The page import route registers the following middleware chain:
packages/import-export/modules/@apostrophecms/import-export-page/index.js
importExportImport: [
self.apos.http.bigUploadMiddleware(),
async (req) => {
return self.apos.modules['@apostrophecms/import-export']
.import(req, self.__meta.name);
}
]
No authorize callback is passed to bigUploadMiddleware().
The bigUploadMiddleware() implementation explicitly supports an authorize callback and performs that authorization before processing the aposBigUpload protocol when supplied.
Without that callback, requests containing:
aposBigUpload[type]=start
aposBigUpload[type]=chunk
or
aposBigUpload[type]=end
are processed immediately.
The actual authentication check occurs later in:
packages/import-export/lib/methods/import.js
async import(req, moduleName) {
if (!req.user) {
throw self.apos.error('forbidden');
}
This means authentication occurs only after the chunked-upload middleware has already performed server-side work.
An unauthenticated attacker submits an aposBigUpload[type]=start request.
The server generates an upload ID and stores attacker-supplied upload metadata, including the declared chunks count.
The attacker can upload chunk data.
bigUploadChunk() copies attacker-controlled data into:
/big-uploads/<id>-<n>-<chunk>
The attacker sends an aposBigUpload[type]=end request.
bigUploadEnd() begins processing the upload and creates temporary files before invoking the downstream import handler.
Only after this processing completes does execution reach the later authentication check in import().
The attacker-controlled chunks value is also used by bigUploadCleanupOne():
for (const { chunks } of Object.values(bigUpload.files)) {
for (let i = 0; (i < chunks); i++) {
await ufs.remove(...);
}
}
No small upper bound on the declared chunk count appears to be enforced at upload initialization.
This allows an unauthenticated attacker to increase the number of filesystem cleanup operations performed for an upload.
The following reproduction was performed only against an isolated test environment.
curl -s -X POST \
'http://localhost:3000/api/v1/@apostrophecms/page/importExportImport?aposBigUpload[type]=start' \
-H 'Content-Type: application/json' \
--data '{"files":{"file":{"name":"evil.tar.gz","size":4,"type":"application/gzip","chunks":1}}}'
The server returns an upload ID despite the request having no authenticated session.
printf 'PWN!' >/tmp/chunk.bin
curl -s -X POST \
'http://localhost:3000/api/v1/@apostrophecms/page/importExportImport?aposBigUpload[type]=chunk&aposBigUpload[id]=<ID>&aposBigUpload[n]=0&aposBigUpload[chunk]=0' \
-F 'chunk=@/tmp/chunk.bin;type=application/octet-stream'
The request succeeds and causes server-side upload storage to be used.
curl -i -X POST \
'http://localhost:3000/api/v1/@apostrophecms/page/importExportImport?aposBigUpload[type]=end&aposBigUpload[id]=<ID>'
Observed behavior:
start returns HTTP 200 and an upload ID without authentication.chunk returns HTTP 200 and results in server-side chunk storage.end eventually reaches the downstream authentication check and is rejected.In my isolated harness:
chunks=1 resulted in one cleanup removal attempt.chunks=50 resulted in 50 cleanup removal attempts.This demonstrates that the attacker-controlled chunk count directly influences server-side cleanup work.
The vulnerability allows an unauthenticated remote attacker to cause server-side storage and filesystem operations that should only be reachable by authorized import users.
Possible consequences include:
Authentication is enforced in the downstream import handler rather than before the chunked-upload middleware.
The middleware itself already supports an authorize callback specifically for preventing unauthorized use of the big-upload functionality.
Require authentication before any aposBigUpload operation is processed.
For example:
authorize callback to bigUploadMiddleware() on all import routes.start, chunk, or end.start, chunk, and end requests are rejected before upload state or files are created.Relevant reviewed commit:
d3ff8c9bb001be1acf7fdc3f035190250ac64b45
Kai Zhi
GitHub:
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Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.