The Instance Metadata Service (IMDS) endpoint, specifically the 169.254.169.254 path, acts as a critical vulnerability, allowing attackers to leverage Server-Side Request Forgery (SSRF) to steal temporary IAM security credentials. To mitigate this risk, security best practices demand enforcing IMDSv2, implementing strict IAM least-privilege roles, and utilizing network-level blocks. Read the full technical breakdown at Medium.
AdministratorAccess or broad S3FullAccess policies to web-facing servers.Credential Retrieval: By appending the role name to the URL (e.g., .../security-credentials/MyRoleName), a user can retrieve an Access Key, Secret Key, and Session Token to perform actions authorized by that role. Security Implications & SSRF Ensure IAM roles attached to EC2 instances only
169.254.169.254 is a special link-local address reserved for metadata services. It is not reachable from the public internet — only from within the virtual network of the cloud provider or from the instance itself. Credential Retrieval : By appending the role name
Recommendations * Validate and sanitize user-supplied URLs. * Block requests to internal IP ranges like 254.169.254 (IMDS) * Log a... Hacking Articles Cloud Instance Metadata Services (IMDS) - SANS Institute The Instance Metadata Service (IMDS) endpoint
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The Goal: The attacker is looking for "Keys to the Kingdom." By fetching these credentials, they bypass traditional firewalls and network security because the request originates from a "trusted" internal source. Remediation Strategies
Enforce IMDSv2: AWS now supports IMDS version 2, which requires a session-oriented request (a PUT request to get a token first). This effectively mitigates most SSRF attacks because attackers typically can only control the URL of a GET request.