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

The string you provided is not a real protocol, standard, or official keyword. It is a URL-encoded absolute file path.

If we decode the %3A, %2F, and %2A characters back to their original form, it reads:

callback-url-file:///home/*/.aws/credentials

Given the components, a scenario where this might come up involves:

  • URL Encoding 3A-2F-2F: The string 3A-2F-2F represents URL-encoded characters: callback-url-file-3A-2F-2F-2Fhome-2F-2A-2F.aws-2Fcredentials

    So, 3A-2F-2F translates to :/, which might appear in a URL or path to indicate a protocol and path but seems misplaced or incorrectly represented in your context.

    • Imagine you run a concierge service. You tell the concierge, "Anyone who brings a valid ticket can ask you to read any document."

    An attacker hands you a ticket that says: "Read the file at /home/*/.aws/credentials."

    If your concierge does it, they just handed over the keys to your castle. The string you provided is not a real

    The file:// callback is that malicious ticket.

  • Air-gapped or restricted systems

  • Non-browser tools

  • Single sign-on (SSO) integration

    • Feature name:
    Local File URI Callback for Credential Delivery

    Callback URL format:
    callback-url-file:///home/*/.aws/credentials

    Purpose:
    Securely deliver temporary AWS credentials (or other tokens) from a web auth flow directly into a local credentials file on disk, using a file-based callback instead of an HTTP local server.

    The callback “handler” (OS-level helper or CLI daemon) interprets the file:// scheme: URL Encoding 3A-2F-2F : The string 3A-2F-2F represents

    # Pseudo-handler
def handle_file_callback(uri, credential_data):
    path = parse_file_uri(uri)  # /home/alice/.aws/credentials
    validate_path_safety(path)
    with open(path + ".tmp", "w") as f:
        f.write(format_credentials(credential_data))
    os.rename(path + ".tmp", path)
    return "Credential write successful"