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What does it actually mean when the HTTPS icon is red and crossed out in Chrome?

Does this mean that the site is vulnerable to a Man in the Middle Attack? Is it safe or not?

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When the https portion of the URL in Chrome has a red line through it, there is a problem with the security of the site you are going to. To see exactly what the problem is, you need to click on the padlock and see the detailed connection info.

Detailed connection info is documented here.

If you see green padlock, then you've established a secure connection with a trusted site, and do not need to worry about MITM attacks.

If you see yellow bang, then the connection is unencrypted, and subject to MITM attacks.

If you see grey padlock or red padlock, then either the connection is only partially encrypted or it's encrypted with a party that's not trusted (e.g., a self signed cert, name mismatch, or imposter). In these cases you may be subject to a MITM attack.

With these last two, the level of exposure varies. It might be that the remote site is properly encrypted, but just happens to have a few "IMG SRC=http://..." tags that cause mixed content. That "mixed content" can be sniffed on the network. Or, it might be that you've gone to an impostor site "gooogle.com" instead of "google.com", and everything you send is encrypted but going to a malicious attacker. Or anywhere in between. The rule of thumb is, essentially, unless you understand why it's red, you shouldn't trust it.

  • 1
    Ok thanks for the answer. How serious is this "may be subject to MITM attack" ? I mean is this something that I should be worry about. For example when I see that in ecommerce website. Can someone for example use Wireshark and sniff the packets in local network? Many Thanks. – Michal Koczwara Apr 10 '15 at 19:32
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    Add to this:As of Chrome 42, sites using SHA1-signed certs expiring in 2017 will get the red X icon, and sites using SHA1-signed certs expiring in 2016 gets the yellow triangle. – KristoferA Apr 11 '15 at 0:33
  • Stackoverflow.com is getting the red x right now for some reason – Kolob Canyon Sep 15 '16 at 18:27
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A crossed out https could mean that the certificate uses the dated "SHA-1" security which is not as secure as it was at its induction 20 years ago. Chrome is simply telling us that. IE and Firefox are not yet reporting sites that use "SHA-1" but will soon. To verify this is the problem, I suggest you open the website in one of the other browsers to see if they state a https connection. If not, then the websites certificate may be something other than the "SHA-1" issue.

0

You're referring to when web browsers draw a red line through the "https://" in their URL bars.

It means that the browser does not trust the certificate that the site is using, for many possible reasons:

  • it isn't signed by one of the root CA certificates that the browser implicitly trusts
  • it's signed by a root CA certificate that the browser used to trust, but doesn't any more because the CA turned out to a rogue
  • the certificate has expired
  • the certificate has been revoked by its creator
  • the certificate says it is for another site, not the site you're looking at

...but nonetheless you asked that a security exception be made and you be allowed to see the site anyway.

You and your browser are vulnerable to a MitM attack, but remember that every site in the world that begins "http://" rather than "https://" is also vulnerable to a MitM attack, and there will be no warnings or red flags about it.

If you see the "https" scored out in your browser, then you have about the same level of security as a regular "http" website, so you should only use it if you're happy with no guarantee of privacy or authenticity.

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    I dont agree on the statement that a invalid https is same as http. A https site with a broken/invalid/Anonymous authentication, does still protect against passive eavesdropping on for example WIFI networks, since no information is passed that would allow a adversiary to decrypt the traffic. The adversiary would have to insert themselves between and modify the traffic to be able to eavesdrop. – sebastian nielsen Apr 10 '15 at 16:30
  • I would make bullet 5 "not the site you requested". Name mismatch can mean either (1) you got connected to the intended site, but it used a cert with the wrong identity(ies), or (2) you got connected to a wrong site, either by mistake or malice, and it is using a cert that does match the data you're "looking at" but not the site you asked for and wanted. – dave_thompson_085 May 1 '15 at 8:39

protected by Community Sep 19 '15 at 17:45

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