Impact
An attacker can use crafted requests to bypass metadata bucket name checking and put an object
into any bucket while processing PostPolicyBucket. To carry out this attack, the attacker
requires credentials with arn:aws:s3:::* permission, as well as enabled Console API access.
Patches
commit 67f4ba154a27a1b06e48bfabda38355a010dfca5
Author: Aditya Manthramurthy <donatello@users.noreply.github.com>
Date: Sun Mar 19 21:15:20 2023 -0700
fix: post policy request security bypass (#16849)
Workarounds
Browser API access must be enabled turning off MINIO_BROWSER=off allows for this workaround.
References
The vulnerable code:
// minio/cmd/generic-handlers.go
func setRequestValidityHandler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// ...
// For all other requests reject access to reserved buckets
bucketName, _ := request2BucketObjectName(r)
if isMinioReservedBucket(bucketName) || isMinioMetaBucket(bucketName) {
if !guessIsRPCReq(r) && !guessIsBrowserReq(r) && !guessIsHealthCheckReq(r) && !guessIsMetricsReq(r) && !isAdminReq(r) && !isKMSReq(r) {
if ok {
tc.FuncName = "handler.ValidRequest"
tc.ResponseRecorder.LogErrBody = true
}
writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(ErrAllAccessDisabled), r.URL)
return
}
}
// ...
donatello Remediation developer
harshavardhana Remediation verifier
RicterZ Analyst
Impact
An attacker can use crafted requests to bypass metadata bucket name checking and put an object
into any bucket while processing
PostPolicyBucket. To carry out this attack, the attackerrequires credentials with
arn:aws:s3:::*permission, as well as enabled Console API access.Patches
Workarounds
Browser API access must be enabled turning off
MINIO_BROWSER=offallows for this workaround.References
The vulnerable code: