internet-explorer-8 - IE8 reporting its user agent string as IE9

Question

I've got a curious problem with a friend's computer. Although I've verified he's using Internet Explorer 8.0.6001.18702 on Windows XP (up to date with all things from Microsoft Update).

However, here is the user agent string it reports:

Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C)

This is bizarre for a number of reasons:

• IE8 is reporting that it's IE9. The Trident/4.0 definitely verifies that it's IE8. This is referenced by the official Microsoft documentation on the user agent string: http://msdn.microsoft.com/en-us/library/windows/desktop/ms537503(v=vs.85).aspx
• I've only ever seen Mozilla/5.0 in the user agent string for actual versions of IE9.

I'm stumped. We've done a reset of IE (KB923737 at http://support.microsoft.com/kb/923737), I've disabled all extensions/addons inside IE, and there doesn't seem to be anything installed that would be purposefully altering the user agent string. I've also dug into the registry to see if the user agent string is being spoofed, and it is at the default (unaltered).

Anyone have any ideas of what I should look at or try next...or what might be responsible for IE8's apparent identity crisis?

Answer 1

我们有一个客户有同样的问题。也被难住了。我们改为使用 TRIDENT 和 MSIE 编号来准确检测他们使用的内容。

如果他们使用的是 Trident 4，它要么是 IE 8（或者是 IE 7，因为兼容模式），但没有更高的版本。其他版本的 IE 也一样。Trident 5 不能高于 IE 9 等。