Automatically rotated access tokens for the service account assigned to the resource. 2. How to Fetch Service Account Metadata
The specific path /instance/service-accounts/ is where your VM goes to find out .
Let's dissect the fetch URL to understand its components: Automatically rotated access tokens for the service account
The phrase you provided refers to a specific often used to retrieve information about a virtual machine's service accounts. In a security context, this specific string pattern—especially with the "fetch-url" prefix—is frequently associated with Server-Side Request Forgery (SSRF) vulnerabilities or CTF (Capture The Flag) security challenges.
To "prepare a feature" around this functionality, you are likely looking to either implement a legitimate data-fetching mechanism for a VM or build a security-focused feature to detect or prevent SSRF attacks. 1. Functional Feature: Service Account Metadata Fetcher Let's dissect the fetch URL to understand its
$ curl -H "Metadata-Flavor: Google" \ "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/"
If you see this string in your logs, it is not a glitch. It is a whisper from the internet, telling you that someone just tried to pick the lock on your front door. Cloud Run revision
Check the VM details in the GCP Console. Ensure a Service Account is attached. If "None" is selected, the metadata server has no credentials to return.
url = "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/" req = urllib.request.Request(url, headers="Metadata-Flavor": "Google") with urllib.request.urlopen(req) as response: data = response.read().decode() print(data)
Every Compute Engine VM, GKE node, Cloud Run revision, and many other GCP serverless environments run a local at the non‑routable IP address 169.254.169.254 and the hostname metadata.google.internal . This server exposes a REST API over HTTP (no TLS required, because the traffic never leaves the physical host). It provides: