When an EC2 instance is launched, it can access its own metadata, including IAM security credentials, through the Instance Metadata Service. This is particularly useful for applications running on the instance that need to interact with AWS services. Instead of having to manage access keys and secrets directly on the instance, which can be a security risk, the instance can request temporary security credentials that can be used to access AWS resources.
aws s3 ls --profile stolen aws ec2 describe-instances --region us-east-1
The URL provided refers to the . Purpose and Function
Understanding SSRF and the AWS Metadata Vulnerability The string request-url-http-3A-2F-2F169.254.169.254-2Flatest-2Fmeta data-2Fiam-2Fsecurity credentials-2F represents a URL-encoded payload frequently used by security researchers, attackers, and automated scanners. Decoded, it targets a well-known administrative endpoint: When an EC2 instance is launched, it can
The most effective way to stop this specific attack is to enforce the use of AWS Instance Metadata Service Version 2 (IMDSv2). Unlike the original version (IMDSv1), which uses a simple GET request, IMDSv2 is session-oriented. It requires a PUT request to generate a temporary token before any metadata can be retrieved. Since most SSRF vulnerabilities only allow GET requests, IMDSv2 effectively neutralizes the threat. Sanitize User Input
: Requests the name of the IAM role attached to the EC2 instance.
An SSRF attack occurs when a vulnerable web application (like a "URL preview" or "image uploader") is tricked into making a request to an internal resource that the attacker cannot reach directly. aws s3 ls --profile stolen aws ec2 describe-instances
Do you need a or script to safely disable IMDSv1 across your environment?
In cloud ecosystems like AWS, the IP address 169.254.169.254 is accessible only from within the running virtual machine (EC2 instance). It requires no prior authentication. If an attacker finds a parameters-based URL input field (e.g., a file uploader, profile picture importer, or web webhook generator) that suffers from SSRF, they can insert this IP.
aws ec2 modify-instance-attribute --instance-id i-xxxxxx --metadata-options "HttpTokens=required,HttpEndpoint=enabled" Use code with caution. 2. Restrict IAM Roles (Least Privilege) Unlike the original version (IMDSv1), which uses a
Securing this endpoint requires a multi-layered defense strategy focusing on updated protocols and strict permission management. 1. Enforce IMDSv2 (The Most Effective Defense)
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