Callback-url-file-3a-2f-2f-2fhome-2f-2a-2f.aws-2fcredentials Jun 2026

In AWS environments, developers often store credentials locally to allow scripts or the AWS CLI to interact with services like S3, EC2, or Lambda. This file is usually located at ~/.aws/credentials .

The callback URL /home/*/.aws/credentials is likely used in the context of AWS authentication flows, such as: callback-url-file-3A-2F-2F-2Fhome-2F-2A-2F.aws-2Fcredentials

AWS SDK for JavaScript and AWS SDK for Python (Boto3) . 2. AWS Step Functions Callback In AWS environments

The decoded string is: callback-url-file:///home/*/.aws/credentials we must decode the URL-encoded string:

After callback writes data:

I’ve been looking into how common "callback URL" parameters can be weaponized to exfiltrate sensitive cloud metadata. A common payload I'm seeing in logs looks like this: ?callbackUrl=file:///home/*/.aws/credentials 🔍 What is happening? Attackers use the

To understand the risk, we must decode the URL-encoded string: