[Website Vulnerability] Open Redirect

[apekz]

Hi Arduino,

Unvalidated redirects and forwards are possible when a web application accepts untrusted input that could cause the web application to redirect the request to a URL contained within untrusted input. By modifying untrusted URL input to a malicious site, an attacker may successfully launch a phishing scam and steal user credentials. Because the server name in the modified link is identical to the original site, phishing attempts may have a more trustworthy appearance. Unvalidated redirect and forward attacks can also be used to maliciously craft a URL that would pass the application’s access control check and then forward the attacker to privileged functions that they would normally not be able to access.

Reference: https://www.owasp.org/index.php/Unvalidated_Redirects_and_Forwards_Cheat_Sheet

I've found a bug in your website which allows authenticated user to redirect to a malware/phishing site and think it's safe because it comes from your site. In this way the users credentials can be hacked.

https://auth.arduino.cc/login?redirect_uri=

redirect_uri is the vulnerable parameter
Let's try to add some website.

https://auth.arduino.cc/login?redirect_uri=https://www.phishingnmalware.com/

If you click that link, you'll get redirected to phishingnmalware.com

Preventing Unvalidated Redirects and Forwards
Safe use of redirects and forwards can be done in a number of ways:

Simply avoid using redirects and forwards.
If used, do not allow the url as user input for the destination. This can usually be done. In this case, you should have a method to validate URL.
If user input can’t be avoided, ensure that the supplied value is valid, appropriate for the application, and is authorized for the user.
It is recommended that any such destination input be mapped to a value, rather than the actual URL or portion of the URL, and that server side code translate this value to the target URL.
Sanitize input by creating a list of trusted URL's (lists of hosts or a regex).
Force all redirects to first go through a page notifying users that they are going off of your site, and have them click a link to confirm.

Best Regards,
Jolan Saluria

[mastrolinux]

This has been fixed some weeks ago.