Google 'suspends' CNNIC from Chrome's certificate store

Posted by   Virus Bulletin on   Apr 2, 2015

Chinese certificate authority told to re-apply.

When a web client, such as a browser, attempts to make an HTTPS connection, it needs to know that no man-in-the-middle attack is taking place. The web server therefore proves its authenticity by presenting the client with a certificate. This certificate is cryptographically signed by a certificate authority (CA), whose certificate is in turn signed by another CA until this chain reaches a CA whose public key is hard-coded in the browser or on the operating system.

This model is often said to be broken. After all, it only takes one root CA to trust an intermediate CA that doesn't check too carefully who is applying for certificates for someone to be able to perform a man-in-the-middle attack on encrypted Internet traffic.

Indeed, this happened recently when someone was able to register the email address hostmaster@live.fi (live.fi is the Finnish version of Microsoft's live.com webmail offering) and use this to obtain a certificate for the domain. Thankfully, the certificate was only created to make a point.

In another recent story, Egypt-based MCS Holdings, an intermediate CA whose certificate was signed by China's CNNIC, created a number of certificates for Google domains. Although these domains were likely intended for internal tests, Google was understandably upset when it discovered the issue - explaining the situation in a blog post.

Now, in an update to its blog post, Google has effectively announced that it has suspended CNNIC from the root store of its Chrome browser.

Cryptography doesn't 'do' suspensions. What Google will do instead is to remove the root certificate from the store and create a whitelist of CNNIC's existing certificates, to prevent users who rely on them from getting alerts about invalid certificates (alerts which are at the least very unwise to bypass). It is worth nothing that Chrome is a very popular browser in China.

Google has said that CNNIC is welcome to reapply once 'suitable technical and procedural controls are in place'. One of these controls is certificate transparency, which will help detect fraudulent certificates. CNNIC probably has little choice but to do so, despite calling Google's decision 'unacceptable and unintelligible'.

For MCS Holdings, though, this will come too late. Trust in its certificates has already been revoked by Mozilla and Microsoft. The company's own investigation - the first conclusion of which is that it is pretty awesome - certainly doesn't inspire confidence.

Though broken in a strict academic sense, the quick discovery of the rogue certificates and Google's further handling of the case shows that the CA model's error-correcting capabilities are actually pretty good. As such, the huge problems that exist in theory are, in practice, mitigated very well.

Posted on 02 April 2015 by Martijn Grooten

twitter.png
fb.png
linkedin.png
hackernews.png
reddit.png

 

Latest posts:

VB2019 paper: Geost botnet. The story of the discovery of a new Android banking trojan from an OpSec error

OpSec mistakes are what lead to many malware discoveries, and in the case of the Geost Android botnet the mistake was a really interesting one. Today we publish the VB2019 paper by Sebastian García, Maria Jose Erquiaga and Anna Shirokova on the Geost…

Analysis of malware responsible for sextortion spam that mines for Monero on the side

VB2019 Platinum partner Reason Cybersecurity presents a threat analysis report on the Save Yourself malware.

Guest blog: Threat intelligence – a unifying force of the future

In a guest blog post VB2019 Platinum partner Reason Cybersecurity looks to the future of threat intelligence.

Guest blog: Why we should be paying more attention to Linux threats

In a guest blog post VB2019 Silver partner Intezer outlines the importance of paying attention to Linux threats.

New Emotet spam campaign continues to bypass email security products

On Monday, the infamous Emotet malware resumed its spam campaign to spread the latest version of the malware. As before, the malware successfully bypasses many email security products.

We have placed cookies on your device in order to improve the functionality of this site, as outlined in our cookies policy. However, you may delete and block all cookies from this site and your use of the site will be unaffected. By continuing to browse this site, you are agreeing to Virus Bulletin's use of data as outlined in our privacy policy.