When a virtual machine (VM) is launched in a cloud environment, it's assigned an instance ID and a set of metadata, including information about the instance's configuration, networking, and storage. The metadata service provides a way for the instance to access this metadata.
In the original version (IMDSv1), the request was a simple HTTP GET request (as described above). IMDSv2 adds a mandatory session layer: An attacker changes the URL to:
The callback URL http://169.254.169.254/latest/meta-data/iam/security-credentials/ represents a cornerstone in the secure operation of AWS instances. By providing a standardized method for instances to obtain temporary security credentials based on their IAM roles, AWS enables secure, scalable, and manageable access to resources. This approach underscores the importance of secure design in cloud infrastructure, balancing the need for access with the imperative of protection against unauthorized access and data breaches. As cloud computing continues to evolve, the principles embodied by this callback URL will remain essential in maintaining the integrity and security of cloud-based systems. including information about the instance's configuration
http://169.254.169 is a classic SSRF attack payload designed to exploit the AWS Instance Metadata Service (IMDS) to retrieve temporary, sensitive IAM security credentials. If successful, this attack allows unauthorized access to temporary AWS access keys, secret keys, and session tokens, enabling potential AWS environment compromise. Protection requires enforcing IMDSv2, input sanitization, and restricting egress traffic to the 169.254.169.254 IP address. AWS enables secure
The endpoint http://169.254.169.254/latest/meta-data/iam/security-credentials/ is the backbone of secure, passwordless authentication for AWS workloads. It allows servers to identify themselves to the cloud without the risks associated with hardcoded passwords.