Uncovering the Mystery of the Fetch URL: http://metadata.google.internal/computeMetadata/v1/instance/service-accounts
Zero typed the malicious payload into their terminal:
The metadata server only supports HTTP, not HTTPS. This is safe because it is a non-routable, link-local address. Uncovering the Mystery of the Fetch URL: http://metadata
Rotate Credentials: Although service account keys rotate automatically in the metadata server, it's essential to monitor and manage access.
Required Header: You must include Metadata-Flavor: Google in all requests to prevent common SSRF bypasses. Common Sub-Paths: Required Header: You must include Metadata-Flavor: Google in
METADATA_URL = "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token" headers = "Metadata-Flavor": "Google"
http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token why it exists
This article breaks down what this URL is, why it exists, and how it enables applications to authenticate securely without hard-coded keys.