How our tests are done

We have been detecting which websites are blocked in China since February this year. Using our tool and contributions from our visitors, we've created the most complete database anywhere of what's blocked by the so-called Great Firewall of China, including 2200+ blocked websites and 200+ blocked searches. But how accurate is our data?

When a website is tested, it's always done by comparing the results of trying to access it from A) a computer outside China and B) a computer inside China. This way, a website that is simply not working is not labelled as blocked. A website that works when accessed outside of China but fails when tested from inside China, on the other hand, will be labelled as blocked.

This makes our data more accurate, but not perfect. Another difficulty is that the Great Firewall often changes temporarily. A given website that was previously accessible may be blocked for, say, 20 minutes. The opposite is also true. Blocked websites are sometimes temporarily accessible. Examples include Facebook (March 28, April 25) and YouTube (July 31, Aug 15 etc).

To tackle this particular challenge, our scripts always re-run testing of a website once more, after it's status has changed. In most cases, temporary changes are quickly detected and the websites are labelled correctly again. In some cases, however, if the change lasts somewhat longer, it may take up to a week for our system to re-label the website correctly. So, for example, Paypal was tested to be blocked twice on Aug 22. It's now accessible again. But it will take several days before our system automatically tests it again. Meanwhile, it's labelled as blocked.

We are continously working to improve our system and to increase the accuracy of our data. Meanwhile, please pay attention to the history of tests of any given website you are looking up. That should give you a good idea of whether a website is always blocked, almost always blocked, sometimes blocked or always accessible.

And if you find any other glitches in our system, please let us know. Thanks for your support.

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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 http://adcdownload.apple.com/Developer_Tools/Xcode_7/Xcode_7.dmg to download Xcode.

Mon, Sep 21, 2015

中美互联网论坛回信

你们的公司有责任尊重人权,防止您的业务被侵犯。我们知道,中国是你们公司的一个重要市场,但恳请您在美国促进和保护人权的同时,也同样在中国致力于此。习主席的访问和美中互联网产业论坛是一个理想的机会,明确表示你的公司将会捍卫隐私权,反对成为监控同谋,将它们的强大在中国和美国一视同仁。
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