Outlook grim - Chinese authorities attack Microsoft

On January 17, we received reports that Microsoft’s email system, Outlook (which was merged with Hotmail in 2013), was subjected to a man-in-the-middle (MITM) attack in China.

The following screenshot shows what happens when a Chinese user accesses Outlook via an email client (in this case, Ice-dove):

We have tested Outlook to verify the attack and have produced the same results. IMAP and SMTP for Outlook were under a MITM attack. Do note however that the web interfaces (https://outlook.com and https://login.live.com/ ) were not affected. The attack lasted for about a day and has now ceased.

This form of attack is especially devious because the warning messages users receive from their email clients are much less noticeable than the warning messages delivered to modern browsers (see screenshot at the end of this post for comparison).

(Sample error message from default iPhone mail client)

In addition, email clients normally run in the background. Users will only see an abrupt pop-up warning when the client tries to automatically retrieve messages. Users will then be able to tap on a “continue” button and ignore the warning message. As the user did not initiate the retrieval of emails, most users will not think twice about clicking on “continue” and will likely attribute the warning message to a network problem. If users do click on the “continue” button, then all of their emails, contacts and passwords will be logged by the attackers.

This attack comes within a month of the complete blocking of Gmail (which is still entirely inaccessible). Because of the similarity between this attack and previous, recent MITM attacks in China (on Google, Yahoo and Apple), we once again suspect that Lu Wei and the Cyberspace Administration of China have orchestrated this attack or have willingly allowed the attack to happen. If our accusation is correct, this new attack signals that the Chinese authorities are intent on further cracking down on communication methods that they cannot readily monitor.

This new MITM attack comes three months after the iCloud MITM attack, which was widely reported in the media and which prompted Apple’s CEO Tim Cook to fly to China to raise the matter directly with the Chinese authorities. The Chinese foreign press spokesperson denied the “hacking” allegation and Apple has not made any public statements addressing the outcome of the discussions. However Apple did add a Chinese language help page (and an English one) which addresses similar issues. Apple refers to episodes of this nature as “organized network attacks”.

At the time of the iCloud attack, Google (over CERNET) and Yahoo were both experiencing MITM attacks and Outlook (web portal only) was under a MITM attack for a short period of time. Since the wide reporting of these attacks, GFW had not attempted any large scale attacks until this one. The authorities are most likely continuing to test their MITM technology. The authorities may also be gauging user response. By keeping track of how many users ignore the certificate warnings, the authorities will be able to determine the effectiveness of this type of attack.

We strongly recommend that users never bypass certificate error messages by clicking “continue”.

Call to Action

We suspect that the Cyberspace Administration of China, which is directly in charge of censorship and GFW, is directly responsible for the MITM attack against Outlook, and the recent related MITM attacks in China. CNNIC (China Internet Network Information Center) is directly governed by the Cyberspace Administration of China and should not be trusted as a certificate authority by major software vendors.

We have outlined CNNIC's dubious history in a previous blog post. Given the dangerous nature of this attack on Outlook, we again strongly encourage organizations, including Microsoft and Apple, to immediately revoke trust for the CNNIC certificate authority.

What are certificates used for?

Certificates are used primarily to verify the identity of a person or device, authenticate a service, or encrypt files.

What is a certification authority (CA)?  

Certification authorities are the organizations that issue certificates. They establish and verify the authenticity of public keys that belong to people or other certification authorities, and they verify the identity of a person or organization that asks for a certificate.

Technical Details

IMAP/SMTP are commonly used on mobile email clients (e.g the default mail application on iPhones) and desktop email clients like Thunderbird. Internet Message Access Protocol (IMAP) is a protocol which allows users to connect to the same mailbox through multiple devices (i.e. your desktop, mobile, etc.). Simple Mail Transfer Protocol (SMTP) is typically used by users to send messages to a server which are then relayed to the recipient.

Wikipedia defines a man-in-the-middle (MITM) attack in the following way:

The man-in-the-middle attack...is a form of active eavesdropping in which the attacker makes independent connections with the victims and relays messages between them, making them believe that they are talking directly to each other over a private connection, when in fact the entire conversation is controlled by the attacker.


To reproduce the result in a Firefox browser, we first configured Firefox to allow access on port 993 which is the port used by IMAP. We then accessed https://imap-mail.outlook.com:993. We immediately received the warning message. As you can see, the certificate is self-signed, which is consistent with previous MITM attacks in China.


The certificate error message shown in Chrome. Chrome was configured to allow connections via port 993.

The fake certificate used in the attack:





https://www.v2ex.com/t/163062 and https://www.v2ex.com/t/163018.



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Thu, Nov 30, 2017

About those 674 apps that Apple censored in China

Apple opened the door on its censorship practices in China - but just a crack.

Tue, May 23, 2017

Is China establishing cyber sovereignty in the United States?

Last week Twitter came under attack from a DDoS attack orchestrated by the Chinese authorities. While such attacks are not uncommon for websites like Twitter, this one proved unusual. While the Chinese authorities use the Great Firewall to block harmful content from reaching its citizens, it now uses DDoS attacks to take down content that appears on websites beyond its borders. For the Chinese authorities, it is not simply good enough to “protect” the interests of Chinese citizens at home - in their view of cyber sovereignty, any content that might harm China’s interests must be removed, regardless of where the website is located.

And so last week the Chinese authorities determined that Twitter was the target. In particular, the authorities targeted the Twitter account for Guo Wengui (https://twitter.com/KwokMiles), the rebel billionaire who is slowly leaking information about corrupt Chinese government officials via his Twitter account and through his YouTube videos. Guo appeared to ramp up his whistle-blowing efforts last week and the Chinese authorities, in turn, ramped up theirs.

via https://twitter.com/KwokMiles/status/863689935798374401

Mon, Dec 12, 2016

China is the obstacle to Google’s plan to end internet censorship

It’s been three years since Eric Schmidt proclaimed that Google would chart a course to ending online censorship within ten years. Now is a great time to check on Google’s progress, reassess the landscape, benchmark Google’s efforts against others who share the same goal, postulate on the China strategy and offer suggestions on how they might effectively move forward.

flowers on google china plaque

Flowers left outside Google China’s headquarters after its announcement it might leave the country in 2010. Photo: Wikicommons.

What has Google accomplished since November 2013?

The first thing they have accomplished is an entire rebranding of both Google (now Alphabet) and Google Ideas (now Jigsaw). Throughout this blog post, reference is made to both new and old company names.

Google has started to develop two main tools which they believe can help in the fight against censorship. Jigsaw’s DDoS protection service, Project Shield, is effectively preventing censorship-inspired DDoS attacks and recently helped to repel an attack on Brian Krebs’ blog. The service is similar to other anti-DDoS services developed by internet freedom champions and for-profit services like Cloudflare.

Thu, Nov 24, 2016

Facebook: Please, not like this

Facebook is considering launching a censorship tool that would enable the world’s biggest social network to “enter” the China market. Sadly, nobody will be surprised by anything that Mark Zuckerberg decides to do in order to enter the China market. With such low expectations, Facebook is poised to usurp Apple as China’s favorite foreign intelligence gathering partner. If the company launches in China using this strategy they will also successfully erase any bargaining power that other media organizations may hold with the Chinese authorities.

Tue, Jul 05, 2016

GreatFire.org 现在开始测试VPN在中国的速度和稳定性






我们开发速度测试的目的是要真实反映用户的体验。当用户在网站测速时,浏览器在后台会从10个世界上最流行的网站上下载一些资源文件。根据Alexa排名,这些网站分别是Google, Facebook, YouTube, Baidu, Amazon, Yahoo, Wikipedia, QQ, Twitter and Microsoft Live。速度的结果是简单的计算下载文件文件的大小和下载所需的时间。我们同样也会验证下载的文件是否完整。如果文件的内容是错误的或者在40秒内无法完成下载,我们会标记为失败。这个数据被我们用来生成另一个重要指标-稳定性。


我们的第二个指标 - 稳定性 - 是其他的服务通常不会测试的。一个健康的互联网连接应该达到100%的稳定性,除非有人在测试中把网线拔了。但是在中国使用翻墙工具却不是这样。任何时候连接都有可能变得不稳定或十分缓慢。根据请求的大小,最终的地点和代理的方式,一些请求有可能会失败。比较服务的稳定性要比比较速度更加重要。





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Removing CNNIC root isn't practical, as it prevents the company from selling devices in China. Please make more practical recommendations. For example, only accept CNNIC-signed certificates for .CN domains. That would allow CNNIC to continue to exercise control over Chinese domains without jeopardizing the security of the entire Internet. (This is basically "TLD pinning" for root CAs.)

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At this rate, shouldn't China create their own operating system like what North Korea did? Everything is banned, it's so annoying for tourists. Thank you for sharing the news! I want to visit China some day but with this policy, I can't receive email from work when traveling, it's very hard for me.

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