IE8 running on Windows 7 does not load certain sites

This article applies to:

• SWG 9.x

Question:

• Why do certain HTTP/HTTPS sites not load in Internet Explorer 8 under Windows 7 or Windows 2008 R2, especially when using Identification (Get User Credentials) or Authentication?

Reply:

This behavior seems to be an IE8 limitation – IE8 is sometimes stuck when SWG responds to an HTTP CONNECT request (the start of an HTTPS session) with an HTTP 407 Proxy Authenticate message.  If the message body (the HTML code) is smaller than a certain size, IE8 hangs after a number of consequential requests/responses.

Solution:

Secure Web Gateway appliances can be configured to work around this issue. The issue does not occur if the HTTP message “HTTP 407 Proxy Authenticate” has at least a specific length. This can be achieved by adding additional dummy-data to the Authentication error message.

Since this modification requires root access, please contact Trustwave Technical Support, referring to this issue and article number 13928 (public) / 13710 (internal).