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)


More Blog Posts

Subscribe to our mailing list
Show content from Blog | Google+ | Twitter | All. Subscribe to our blog using RSS.

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.

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.

Mon, Sep 21, 2015



Sat, Sep 19, 2015

Popular Chinese iOS apps compromised in unprecedented malware attack

What happened?

According to recent reports, some versions of Xcode used by developers in China have been compromised and are being used to inject tracking codes in iOS apps without developer knowledge. (1,2). Unaware of the injection, those developers then released their compromised iOS apps to the App Store which were then later approved by Apple. At the time of writing this post, the compromised apps are still available in the App store. Any user who has installed and launched these compromised apps will be a victim of these tracking codes.

This is a significant compromise of Apple’s app store. Apple notoriously manually reviews all app submissions and, in comparison to Android stores, has been relatively malware-free. This is the most widespread and significant spread of malware in the history of the Apple app store, anywhere in the world.

The compromised version of Xcode was hosted on Baidu Pan. It is unlikely that Baidu was aware of the compromised version of Xcode. The company removed the files yesterday when news of the compromise surfaced. Because of slow download speeds from foreign websites in China, many Chinese developers prefer to download apps from domestic websites. Many Chinese also use download software like Xunlei, rather than downloading directly from the official Mac App Store.

According to users reports, many prominent Chinese apps are affected. We have included links to the compromised apps in the list below but DO NOT DOWNLOAD these apps. We are simply linking to them so that users can recognize the apps. Affected apps include:  

Wechat The most popolar messaging app in China 

Wed, Sep 16, 2015



Roya, David, Nick, nweaver, Vern, 和我刚刚完成了关于GFW主动探测系统的研究。这个系统在几年前就被用来探测翻墙工具,比如Tor。我们在之前的博文中介绍过GFW主动探测系统是如何工作的。但有几个问题我们没有回答。比如这个系统的物理结构是怎样的。那些用来主动探测的IP是归GFW所有的么? 有猜测GFW短时间内劫持了部分IP来用来主动探测,但没有证据。这次研究回答了这些问题。


  • 通常来说,如果Tor的某个网桥代理被GFW检测并封锁,它会一直被封锁。但是这意味着网桥代理完全无法访问吗? 我们让中国的VPS一直连接我们控制的网桥代理。我们发现,每25小时,中国的VPS可以短暂的连接到我们的代理网桥。下图显示了这个现象。每个数据点表示中国的VPS试图与网桥代理建立连接。中国联通和中国教育网都有这个周期性现象。有时候,网络安全设备在更新规则时会默认允许所有流量,但我们不知道GFW周期性现象是不是因为这个原因导致的。

  • 我们找到了规律,GFW主动探测的TCP头暗示那几千个IP都来自与同一个地方。下图显示了数据包的初始序号和时间。每个数据点都是一个主动探测连接。如果每个主动探测都是从不同地方发出的,我们应该看到随机的数据点,因为数据包的初始序号是随机选择的。但是下图显示主动探测连接虽然来自不同IP,但是非常有规律。我们认为主动探测的初始序号是按照时间产生的。


Subscribe to our blog using RSS.


this post is awesome, great msg for us, plz update ur blog for daily basis, i am regular visitor of this site, so keep posting for us,

click the below links to create backlink
best free backlink website
click here for msg movie

thanks for this post, keep it up for updating us, i am waiting for ur new article.
IPL 2015 Cricket live score
mps computers
Harjinder Singh

thanks again

Add new comment

Filtered HTML

  • Web page addresses and e-mail addresses turn into links automatically.
  • Allowed HTML tags: <a> <em> <strong> <cite> <blockquote> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
By submitting this form, you accept the Mollom privacy policy.