TOKEN=$(curl -X PUT "http://169.254.169" \ -H "X-aws-ec2-metadata-token-ttl-seconds: 21600") Use code with caution.
solves this by requiring a session-oriented authentication process:
curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169 Use code with caution. Why This Matters for Security curl-url-http-3A-2F-2F169.254.169.254-2Flatest-2Fapi-2Ftoken
: Defines how long the token is valid (in this case, 21,600 seconds or 6 hours). Step 2: Access Metadata
The IP address is a link-local address used by AWS to provide the Instance Metadata Service (IMDS) . Every EC2 instance can query this address to retrieve information about itself—such as its instance ID, public IP, IAM role credentials, and security groups—without needing to call the AWS API externally. The Evolution: From IMDSv1 to IMDSv2 TOKEN=$(curl -X PUT "http://169
: Even if an attacker can execute a GET request through your app, they cannot easily perform the PUT handshake required to get a token. Conclusion
When you see the string curl-url-http-3A-2F-2F169.254.169.254-2Flatest-2Fapi-2Ftoken (which is a URL-encoded version of the path), it refers to this specific two-step process. Step 1: Generate the Token Step 2: Access Metadata The IP address is
Understanding the AWS IMDSv2 Token Fetch Command: curl 169.254.169
In the past (IMDSv1), metadata was accessible via a simple GET request. While convenient, this was vulnerable to attacks. If an attacker could trick a web application into making a request to that internal IP, they could steal sensitive IAM credentials.