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

Because most basic SSRF vulnerabilities only allow attackers to make simple GET requests without custom headers, IMDSv2 completely blocks them from accessing the credentials. 2. Input Validation and Whitelisting

http://169.254.169.254/latest/meta-data/iam/security-credentials/

The use of this callback URL for retrieving IAM security credentials has profound security implications:

In the original version (IMDSv1), the request was a simple HTTP GET request (as described above). IMDSv2 adds a mandatory session layer:

The IP address 169.254.169.254 is a used specifically by AWS to provide instance metadata to the machine itself. It is not accessible from the public internet. The Attack Vector: SSRF Because most basic SSRF vulnerabilities only allow attackers

in this context most likely refers to a successful security test or a "favorable" finding in a security audit where the vulnerability was confirmed. New Zealand Information Security Manual Breakdown of the Payload callback-url

The attacker obtains temporary AWS credentials.

"Code" : "Success", "LastUpdated" : "2024-01-15T12:34:56Z", "Type" : "AWS-HMAC", "AccessKeyId" : "ASIAIOSFODNN7EXAMPLE", "SecretAccessKey" : "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY", "Token" : "IQoJb3JpZ2luX2VjEHsaCXVzLXdlc3Qt...", "Expiration" : "2024-01-15T18:45:33Z"

To understand why attackers target this specific URL, you must understand the role of the Instance Metadata Service. IMDSv2 adds a mandatory session layer: The IP address 169

To mitigate this, AWS introduced , which requires a session-oriented approach:

– Navigates to the folder housing the configuration data for the running instance.

aws ec2 modify-instance-metadata-options \ --instance-id i-1234567890abcdef0 \ --http-tokens required \ --http-endpoint enabled Use code with caution.

This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. AWS Retrieving Security Credentials from Instance Metadata New Zealand Information Security Manual Breakdown of the

To ensure secure usage:

This article decodes that string, explains what it points to, why it is a high-value target for attackers, and how to secure it.

If an attacker can trick your application into "calling back" to this URL, your server will fetch its own secret AccessKeyId SecretAccessKey SessionToken and send them back to the attacker. Recommended Security Post

The first request to that URL may be a test. The second is a takeover.