KB Article | Forcepoint Support

Problem Description

In a deployment that uses URL sandboxing, a user clicks on a link embedded in an email, chooses “Yes” to “Analyze this page?”, and receives an error or partial page. A common error is “Too many redirects.”

What’s going on?


The error is usually the result of a URL Sandbox limitation: Websites that require a cookie are not supported.

With URL sandboxing, when a recipient clicks on a link in a message, and the link or elements associated with the link are considered suspicious, the user is notified and given the option to analyze the page.
Sandbox dialog

If the user selects “Yes”, and the target website relies on a cookie, analysis may return an error or render the page incorrectly.

Here’s what happens:

  1. The website attempts to set a cookie (to track the session); for security reasons the sandbox strips the cookie.
  2. The website then redirects to the original URL with a Set-Cookie header.
  3. When the browser follows the redirect, the web server (origin server) expects to see the cookie.
  4. When it doesn’t see the cookie, it may again perform a redirect to set the cookie, in which case a redirect loop may result. Or, the server might detect that there is no cookie in the redirected request and not display the page correctly.
  5. If there is a redirect loop, the browser eventually detects the loop and returns an error.

If a user must access a link that gets an error (or is otherwise blocked by the URL sandbox), the user should work with Helpdesk to resolve the issue.

  • TRITON AP-EMAIL and Forcepoint Email Security on-premises administrators need to contact Technical Support with the sandboxed URL and request the original URL.
  • Any administrator or end user can check any URL for malicious content by going to the online CSI ACE Insight page (https://csi.websense.com) and entering the URL.

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