To construct a URL in a safer way without using user-controlled data, you need to follow proper parameter encoding and validation practices. This ensures that the URL is constructed securely and prevents potential security vulnerabilities such as injection attacks.
Here is an example of constructing a URL with user-controlled data, which is vulnerable to attacks:
var userControlledData = "https://example.com/page?param=" + userControlledInput;
In this example, the user-controlled input is directly appended to the URL without any validation or encoding. An attacker could exploit this by injecting malicious data or manipulating the URL to perform unauthorized actions.
To avoid such vulnerabilities, you should use proper encoding techniques:
var safeData = encodeURIComponent(userControlledInput);
var url = "https://example.com/page?param=" + safeData;
In this updated example, the user-controlled input is first encoded using the encodeURIComponent() function. This ensures that any special characters are properly encoded, making it safe to include in a URL.
By following this approach, you can construct URLs safely and mitigate the risk of injection attacks.