Sina testing subtle censorship ahead of Tiananmen anniversary

What happened?

On May 31, 2013 at 7am, we observed that searching for keywords that are normally blocked, for example, “六四事件” (June 4th incident), surprisingly returned some results and no censorship notice. This temporary lift of censorship ended at 9am but started and stopped a few more times into early afternoon, as if literally somebody was flipping a switch on and off at Sina headquarters.

Update on June 2: Sina is still constatnly swtiching between those two method.

Update on June 8: From June 3-4th and onwards, Sina Weibo seems to switch back to explicit compelte block for those keywords.

Change in Tact

To understand what is happening you need to be familiar with Sina’s various censorship methods. We observed and reported last year that Sina had implemented new tactics to censor particular keyword searches. Just days before the June 4th anniversary, Sina is again tweaking its censorship mechanisms. During the morning hours of May 31, Sina completely abandoned its old style, explicit approach to censorship, which displayed a message but no search results:

“According to relevant laws, regulations and policies, search results for [the blocked keyword] can not be displayed.”

No, Sina has not suddenly decided to fully support freedom of speech. On the contrary, it would appear that Sina is using more advanced and subtler methods to censor search results. All keywords mentioned below are normally explicitly and completely blocked. But each behaved a little bit differently on the morning of May 31.

Strictly filtering

The results we received when we searched for “六四事件” (June 4th incident) showed that the first page of results displayed not all results but carefully selected results. While the first results page seems to indicate that there are more than 50 pages of results, no results are shown when you click through to the next page or any page beyond the first. This censorship tactic was also employed last year for “香港” (Hong Kong) (Solidot story in Chinese).

Keyword example: “六四事件”(June 4th incident)

Delayed censorship

We have also previously reported that Sina has delayed search results for sensitive keywords.

When testing the delayed censorship tactic, we conducted two simultaneous searches of similar keywords, one sensitive and one non-sensitive. In the case of searching for results for “六四” (June 4), we used “五七” (May 7) as a control group, to be sure that search results were indeed intentionally delayed. As suspected, results for “五七” (May 7) displayed posts that were ten minutes old while the most recent June 4 posts were several hours old.

This indicates a marked improvement on Sina’s time delay censorship mechanism. Previously the default time delay was seven days. It is likely that many Sina Weibo users would find this time delay to be odd but could attribute this to a bug or a glitch in the system. With today’s hours-long time delay, most users will likely think that discussion around this topic is ongoing.

This is an example of censorship at its worst - users suspect their search term might get blocked before they search but instead of a censorship notice they are led to believe that what they are searching for is not sensitive plus not many people are saying anything interesting about the keyword anyway.

A good example of this can be found when searching for “天安门事件” (Tiananmen incident). The current search results do in fact bring up quite a bit of information about an incident which occurred in Tiananmen Square - in 1976.

Keyword example “六四” (June 4th), “天安门事件” (Tiananmen incident), 24周年 (24th anniversary) 法轮功 (Falungong)

Implicit complete censorship

Sina now returns a fake “Sorry, no results can be found” message instead of the normal censorship message that we have come to at once love and hate: “According to relevant laws, regulations and policies, search results for [the blocked keyword] can not be displayed.”

Keyword example: “64事件” (64 incident)

Implicit semi-censorship

Sina returned a partial censorship notice from page 2 onwards. The first page looks completely normal, leading users to believe that there are no decent search results for that keyword - why continue searching?

Keyword example: “天安门大屠杀”

V user only censorship

Some relatively low level sensitive words appear to be totally uncensored in this system. Is this the beginning of successful long tail sensitive keyword search on Sina Weibo?

Update: Earlier we said that some keywords appear to be completely uncensored. We have to admit that Sina even fooled us. Actually, all search results come from V users only. V users on Sina are like verified account on Twitter. Those users are more likely to follow the rules as they might face revoke of V status or block of account.

Keyword example: “游行” (demonstration)


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Tue, Jul 05, 2016 now testing VPN speed and stability in China

There is a commonly held belief in China that if you have a VPN that works then you should keep quiet about it. In terms of freedom of access to information, the problem with this approach is that access to knowledge suddenly is a secret. Today we are launching a project that we hope will destroy that model.

Our newest website, Circumvention Central (CC), aims to provide real-time information and data about circumvention solutions that work in China. Since 2011, we have been collecting data about blocked websites in China and now we will add data about the effectiveness of VPNs and other circumvention tools.

We are launching CC with four main objectives in mind.

Our first objective is to help to grow the number of Chinese who circumvent censorship restrictions in China. By sharing our information and data about these tools, we hope to show a wider audience which circumvention tools are working.

Our second objective is to improve the circumvention experience for users in China by bringing transparency to tool performance. We will measure these tools on speed (how quickly popular websites are loaded) and on stability (the extent to which popular websites load successfully).

Sat, May 07, 2016

The New York Times vs. The Chinese Authorities

Could the New York Times be setting the best path forward for news organizations in China?

Thu, Feb 18, 2016

From the desk of Lu Wei: Apple, encryption and China

Lu Wei, Director of the Cyberspace Administration of China, offers some friendly help to FBI Director James Comey.

Thu, Sep 24, 2015

Apple blocked CNNIC CA months after MITM attacks

In March of this year, Google found unauthorized digital certificates for several Google domains. The root certificate authority for these domains was the China Internet Network Information Center (CNNIC). CNNIC was controlled by the Chinese government through the Ministry of Industry and Information Technology and is now under the management of the Cyberspace Administration of China (CAC). CNNIC was recognized by all major browsers as a trusted Certificate Authority. If CNNIC signs a fake certificate used in a man-in-the-middle attack, no browser will warn of any unusual activity unless the certificate is pinned.

After Google found these unauthorized certificates, both Google and Firefox revoked its trust in CNNIC a few days later, a development we at have adovacting for since 2013. Apple and Microsoft on the other hand, did not revoke their trust in CNNIC, nor did they make any announcements regarding the security compromise.

Wed, Sep 23, 2015

Malicious Xcode could spread via download manager Xunlei

What’s at stake?

We reported last week that popular Chinese iOS apps were compromised in an unprecedented malware attack. We discovered that the source of the infection was compromised copies of Xcode hosted on Baidu Pan. Apple has published an article urging developers to download Xcode directly from the Mac App Store, or from the Apple Developer website and validate signatures. We’ve now discovered that even if a developer uses a download link seemingly from Apple, he might still be possible to obtain a compromised copy of Xcode.

Please note that we do not have evidence that such attacks has happened. But it is an easy attack that anyone can implement.

How does it work?

This compromise happened because of Xunlei. Xunlei is the most popular download manager in China. Much of its popularity is due to the fact they can accelerate download speeds by pulling resources from other Xunlei users as well as cached copies on the Xunlei server. All of this, however, is invisible to users. Users can simply enter a regular http download address into Xunlei  download manager and the download will start. Chinese developers were using direct download addresses such as to download Xcode.

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