int responseCode = connection.getResponseCode(); if (responseCode == 200) // Process the response
auth_req = google.auth.transport.requests.Request() credentials.refresh(auth_req)
Mastering GCP Security: Fetching Access Tokens via metadata.google.internal
The URL string represents a URL-encoded target pattern frequently analyzed in cybersecurity assessments. It highlights a classic payload used to probe or exploit Server-Side Request Forgery (SSRF) vulnerabilities within applications hosted on Google Cloud Platform (GCP). int responseCode = connection
curl -H "Metadata-Flavor: Google" \ http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/ Use code with caution.
Let’s build a small application that runs on a GCE VM, fetches the list of service accounts, then uses the default account to list all buckets in the project.
You can also replace default with a specific service account's email address to get similar information for that specific account. Let’s build a small application that runs on
The endpoint http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/ is a cornerstone of Google Cloud’s security model, enabling applications to obtain identity and access tokens without hardcoded secrets. However, it is also a frequent source of confusion—especially when URLs are improperly encoded, as seen in the keyword fetch-url-http-3A-2F-2Fmetadata.google.internal-2FcomputeMetadata-2Fv1-2Finstance-2Fservice accounts-2F .
The response from the metadata server will be a JSON object containing information about the service accounts associated with your instance:
In GCP, a service account is a special type of account that allows your application to interact with GCP resources without needing to authenticate with a user account. Service accounts are used to authorize access to resources, such as Cloud Storage buckets, Cloud Datastore, or Cloud Pub/Sub topics. However, it is also a frequent source of
You can use curl to fetch the token directly from a terminal within the VM.
Authorization: Bearer <access_token>