Callback-url-http-3a-2f-2f169.254.169.254-2flatest-2fmeta Data-2fiam-2fsecurity Credentials-2f -

The callback URL has various use cases:

: This is the directory path. It tells the metadata service that the request is asking for IAM security credentials associated with the instance's role.

Access AWS resources (S3 buckets, databases, etc.) permitted by that role. Potentially escalate privileges within the AWS environment. 4. Remediation and Prevention

The string callback-url-http-3A-2F-2F169.254.169.254-2Flatest-2Fmeta data-2Fiam-2Fsecurity credentials-2F is a URL-encoded payload. When decoded, it points to: http://169.254.169 The callback URL has various use cases: :

: First, an EC2 instance is launched with an IAM role attached. This IAM role defines the permissions the instance has to access AWS resources.

Given the severity of these threats, a comprehensive defense is required.

The use of the http://169.254.169.254/latest/meta-data/iam/security-credentials/ URL provides several security benefits, including: Potentially escalate privileges within the AWS environment

IMDSv2 adds using PUT :

Ensure your IAM Roles follow the principle of least privilege. Even if an attacker steals the credentials, they cannot access everything.

The vulnerable web server accepts the input, decodes it, and makes a backend HTTP request to the metadata IP on behalf of the attacker. When decoded, it points to: http://169

The most effective defense against SSRF-based credential theft is migrating to . IMDSv2 requires a PUT request to first obtain a session token, which then must be included as a header in subsequent GET requests. This stops most SSRF attacks, which typically only support simple GET requests. Enforce IMDSv2 by setting http_tokens = "required" in your instance metadata options and http_put_response_hop_limit = 1 to prevent forwarding.

"Code" : "Success", "LastUpdated" : "2023-10-01T12:00:00Z", "Type" : "AWS-HMAC", "AccessKeyId" : "ASIAIOSFODNN7EXAMPLE", "SecretAccessKey" : "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY", "Token" : "IQoJb3JpZ2luX2VjELz...", "Expiration" : "2023-10-01T18:00:00Z"

The URL you provided, http://169.254.169 , is the specific endpoint for the . It is used by applications running on EC2 instances to retrieve temporary IAM security credentials.

This threat actor exploited an SSRF flaw in Adminer (CVE-2021-21311) to steal credentials from IMDS, demonstrating that this attack vector has been weaponized by advanced persistent threat groups for years.