I'm accessing Bing (https://www.bing.com) from within China. I got the following information:

enter image description here

How could this happen? HTTPS but not encrypted, and with SSL certificate?

Here is the packet capture using wireshark. Bing's IP is .

A new capture.

  • on the same machine what do you get when you ping bing.com ?
    – elsadek
    Commented Oct 24, 2017 at 6:06
  • 1
    Which browser/OS is this?
    – nulldev
    Commented Oct 24, 2017 at 6:06
  • have you ever installed a cert manually?
    – dandavis
    Commented Oct 24, 2017 at 6:27
  • 6
    Possible duplicate of What does this Https - "not fully secure" warning mean?
    – User1
    Commented Oct 24, 2017 at 15:27
  • 2
    This does not look like a 'not fully secure' warning. This looks like a 'not encrypted' warning. But with a SSL cert. Commented Oct 25, 2017 at 9:13

4 Answers 4


Edit for the pcap: my theory does not hold; the other points are still valid.

I will keep my original, speculational, answer, but TL;DR: if resources are loaded via http, such a warning is warranted.

As the comments go, this seems to be a warning about non-https resources used on the website. This might trigger warnings of that kind and for a good reason:

If scripts are loaded in such a way, a man in the middle can inject scripts that compromise every interaction with such a website (and even more, in case of an exploit being available to the attacker for your browser). Additionally, even other resources could lead to code being executed that was not intended to run in that context.

Now my original answer: This might be a downgrade attack that is allowed by Microsoft.

First off: TLS has two different purposes:

  1. to authenticate the server (and optionally the client) via a public key infrastructure.
  2. to evaluate which encryption capabilities server and client share and choose one of them over an insecure connection.

While the server has been authenticated, it seems that the server and you have established a plain text „encryption“.

Secondly: this might be useful if the client (or server) has very limited computational capabilities. As a mean to allowing access (availability) over secrecy, this can be useful.

Thirdly, my speculation: In this case, it is possible that bing is only allowed operation in China as long as the great firewall can look inside the traffic. Thus, Microsoft might have chosen availability over secrecy, making use of the plain text option to allow for deep packet inspection by the GFC.

  • 7
    For those who are interested: There are two Bings in China, one called China Bing and the other International Bing. Both are censored but if I access international Bing i can get normal encryption.
    – Ryan
    Commented Oct 24, 2017 at 7:34
  • See it here: imgur.com/a/KJE9S
    – Ryan
    Commented Oct 24, 2017 at 7:41
  • 4
    @Ryan: thanks. There is one TCP connection to bing.com in this file (stream 2). But the capture is in the middle of the connection only so that no TLS handshake can be seen. Thus one can not see which cipher gets used. But the application data inside the SSL frames don't look plain text at all. Apart from that the cipher can not really depend on the URL path. I rather suggest that the message you see comes from including some http:// resource inside https://. Commented Oct 24, 2017 at 9:19
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    @Ryan: The new handshake shows clearly the use of a strong cipher (TLS_ECDHE_RSA_WIDTH_AES_128_GCM_SHA256). Based on this I don't believe the theory with using weak or null ciphers. And no, F5 does not mean that the underlying TCP/TLS connections gets recreated, but only that the HTTP request is resent which might be done using an established connection. Commented Oct 24, 2017 at 9:41
  • 1
    @SteffenUllrich The cause might be mixed content. Please review my answer below.
    – Ryan
    Commented Oct 24, 2017 at 9:58

It's not only in Edge, but also IE and Chrome. The reason is now clear: MS does serve content over insecure connections, at least in China. As the Mixed content warnings at the bottom right of the screen shot below indicate, the page requests images over HTTP, making it insecure:

enter image description here

  • 1
    How does the screenshot prove your point? All I am seeing is "mixed content" warnings.
    – Flimm
    Commented Oct 24, 2017 at 13:34
  • 2
    I had a similar question about Pandora on Firefox. This answer was helpful in understanding things. Commented Oct 24, 2017 at 14:25
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    @Flimm1 It is loading mixed content, look at the bottom right. There is source code on the page that is specifically requesting content from an http source, making it insecure.
    – Caimen
    Commented Oct 24, 2017 at 15:33

How could this happen? HTTPS but not encrypted, and with SSL certificate?

There are three ways I can think of that this could happen.

  1. The server is purposefully configured with a null protocol, which is technically allowed under HTTPS, although highly discouraged.

  2. The server is configured with a proper encryption protocol, but has a weakness that allows a hacker to launch a downgrade attack. Such a weakness was found a year or two ago in OpenSSL (see this article) which is a very popular code base on which many web servers are based. There are other attacks as well.

  3. You are in a network environment (which might be all of China) where connections to Bing are intercepted and you are served content with a certificate that is not the original certificate. This sort of setup is common in corporate environments (see this question for details). It would require that your laptop contain a root certificate that is controlled by the party that is performing the interception, e.g. a Chinese CA, which could then issue a certificate that looks exactly like it is owned by Bing.


“Secure” HTTPS means an encrypted connection between the browser and the web server. That's it. That only ensures that the data traveling between your browser and the web server is safe. It does not cover all the spectrum of security.

The site is practically loading mixed content, some content such as images and CSS will be loaded over an insecure channel while the main site content is served secured over HTTPS. As an example, if any of the content uses "form action="http" instead of "form action="https", this contributes to the possibility of site being compromised. In your specific case, there's additionally adobe flash. As long as you have flash content, so practically security is dead anyway. Adobe Flash runs inside the same process and memory as the web browser and frequent bugs in it give hackers lots of easy opportunities to gain access to memory. They then can jump to a specific memory address and do anything from there.

As for the SSL, When you request a HTTPS connection to a website, the website will initially send its SSL certificate to your browser. This certificate contains the public key needed to start the secure session. Based on this initial exchange, your browser and the website then initiate the 'SSL handshake'. The SSL handshake involves the generation of shared secrets to establish a uniquely secure connection between yourself and the website. A lot of things can go wrong here and the secure connection is no longer happening. Many times, it can be due to a compromised browser but it can be because of problems in the site also.

  • 2
    Microsoft doesn't deliver mixed content over insecure channel
    – elsadek
    Commented Oct 24, 2017 at 6:04
  • Yes it often did.
    – Overmind
    Commented Oct 24, 2017 at 6:35
  • 2
    @elsadek it might not be true in China. See my answer.
    – Ryan
    Commented Oct 24, 2017 at 9:56
  • 1
    Why is this downvoted? The only point of disagreement I see in the comments is about mixed content, but the OP's own answer shows there is mixed content. Commented Oct 24, 2017 at 18:47
  • 1
    @reirab: Null cipher is no longer considered valid; any client or server that offers or accepts it is buggy. Commented Oct 24, 2017 at 19:13

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