Last updated: April 29, 2026
Why this module exists. Capital One. Capital One. Capital One. Every cloud security training references it because the chain is iconic: external SSRF → IMDS → IAM credentials → S3 dump. Six years later, IMDSv1 is still enabled on enough EC2 fleets to keep the attack practical. And Azure / GCP have their own metadata-service attack surfaces.
What metadata services do
Every cloud VM needs a way to know its identity, its instance type, its attached IAM role’s credentials, its launch configuration. The cloud provides this via a special HTTP endpoint accessible only from the VM itself:
| Cloud | Endpoint | Auth |
|---|---|---|
| AWS | http://169.254.169.254/latest/meta-data/ | IMDSv1: none. IMDSv2: PUT-derived token. |
| Azure | http://169.254.169.254/metadata/instance?api-version=… | Header: Metadata: true |
| GCP | http://metadata.google.internal/computeMetadata/v1/ | Header: Metadata-Flavor: Google |
The crucial detail: this endpoint is reachable from any process on the VM. Including any process the attacker controls — including a vulnerable web app that does SSRF.
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