To protect your environment from this type of file retrieval attempt, implement the following security layers: Input Validation : Use a strict allowlist for URLs. Never allow the wrappers if the intent is to fetch HTTP/HTTPS resources. Disable Path Traversal : Sanitize inputs to remove sequences like or encoded characters like Use IMDSv2 : If running on EC2, enforce Amazon EC2 Instance Metadata Service Version 2 (IMDSv2)
Now the attacker knows the region. Next, they try: fetch-url-file-3A-2F-2F-2Froot-2F.aws-2Fconfig
The attacker finds a form input, URL parameter, or API endpoint that accepts URLs (e.g., a profile picture uploader, HTML-to-PDF converter, or webhook integrator). To protect your environment from this type of
: This is a common query parameter name used by web applications that fetch remote content (such as loading a user profile picture from a URL, generating PDF reports from a link, or fetching RSS feeds). Next, they try: The attacker finds a form
: Decodes to file:/// . This triggers the URI scheme handler to read local files from the host operating system rather than making an external network request ( http:// ).
On AWS EC2, never store access keys in /root/.aws/credentials . Instead: