Internet outage in China on Jan 21

Yesterday we witnessed one of the largest Internet outages ever in China. We have three theories about why this outage may have occurred - two related to the Falun Gong but our third theory is that the Chinese authorities set out to attack our unblockable mirror websites.

From 15:30 to 16:30 (China time) on January 21, DNS lookup to any domain would incorrectly resolve to 65.49.2.178. Websites inside and outside of China were affected. Even Baidu and Sina were inaccessible. Only software using IP directly (e.g. QQ, VPNs) worked during that time. Attempts to visit any website redirected to http://65.49.2.178, which didn’t respond during that time.  The overwhelming traffic to this IP likely crashed the server.

Timeline

Event

15:15

GFW DNS poisoning begins. First recorded instance.

15:17

Local DNS servers began to cache incorrect responses. Some large websites in China began to be affected e.g Sina Weibo.

 

Incorrect DNS continue to spread through Chinese DNS servers. Major websites including Baidu, Sina affected.

15:39

DNS poisoning lifted by GFW. But local DNS resolvers cached incorrect responses. Users continued to experience outage.

16:00

ISPs around China were manually flushing DNS caches and connections were gradually restored.

We have conclusive evidence that this outage was caused by the Great Firewall (GFW). DNS poisoning is used extensively by the GFW. Some articles that have appeared about this outage suspected that the root DNS server in China was hacked and all domains hijacked to 65.49.2.178. This could explain why DNS servers in China were poisoned. However, during that time, we see that a lookup to 8.8.8.8, a public DNS operated by Google, returned bogus results if the lookup was done from China. In fact, the Google public DNS was not poisoned; the bogus response 65.49.2.178 could only have been returned by GFW.  If the Chinese root DNS server was hacked, a DNS lookup in China via 8.8.8.8 should have returned a correct response. See the below image from Zhihu.

Our testing system is designed to detect these bogus responses by querying non-existent DNS servers outside of China. Any valid response must come via GFW. We indeed observed such behavior during that time on all domains.  

But why did GFW poison all domains and effectively block all website traffic in China?

This action must have been unintentional. 65.49.2.178 is owned by Dynamic Internet Technology according to an IP lookup, and they are behind the famous circumvention tool FreeGate. Currently, http://65.49.2.178 is a mirror site for dongtaiwang.com, a news portal operated by Falun Gong groups.

Blocking 65.49.2.178

One hypothesis is that GFW might have intended to block the IP but accidentally used that IP to poison all domains.

Hackers

Many Chinese media stated that yesterday’s outage may have been due to a hacking attempt. The IP is operated by Dynamic Internet Technology, “mortal enemy number one” of the Chinese government. Some are suggesting Dynamic Internet Technology is behind the outage. However, hacking into a root DNS resolver is not enough to cause this outage, as we explained earlier in this post. They have to hack into GFW. If they are indeed capable of doing that, they can accomplish so much more than messing the entire Chinese internet up. In addition, 65.49.2.178 during that time was not serving any content and with such traffic, it looks more like a DDOS attack agasint 65.49.2.178. They couldn't use that IP to spread sensitive content during that time. However, from today, they have indeed started to use http://65.49.2.178 to distribute mirrors and stopped within a few hours.

Blocking our mirror sites

Our mirror site for FreeWeibo has attracted considerable attention and GFW has tried multiple times to block us. We automatically rotate backend servers and the GFW automatically scans new URLs and DNS poisons them.  DNS poisoning is not commonly used compared to connection reset. GFW seems to only use DNS poisoning as a last resort when connection reset fails to block a site. Our mirror forces GFW to add hundreds of rule-sets to DNS poisoning daily and perhaps because of this we were responsible for the system crashing. This is supported by the fact that our new backend domains are no longer automatically blocked.

We’re also continuously improving our backends to prevent automatic discovery from GFW. Perhaps the script operated by GFW acquired a “null” domain from us and consequently blocked everything.

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星期二, 7月 05, 2016

GreatFire.org 现在开始测试VPN在中国的速度和稳定性

在中国有一个普遍观念,如果你有一个可以使用的VPN,那么你应该保持沉默。就信息自由而言,这种观念的问题在于获取知识竟成了一种秘密。今天,我们推出一个项目,希望能够摧毁这种模型。

我们最新的网站,翻墙中心,目的在于实时提供那些能够在中国使用的翻墙方案的信息和数据。在2011年以来我们就已经开始收集在中国被屏蔽的网站,现在我们也将增加那些可用的VPN和其他翻墙工具。

我们发布翻墙中心主要有四个目的。

我们的首要目标是助长使用翻墙工具的国人的数量。通过分享我们这些工具的信息和数据,我们希望对更广泛的受众展示那些工具时可以使用的。

我们的第二个目标是通过带来工具性能的透明化来提升中国用户的翻墙体验。我们将会测试工具的速度(流行网站的加载速度)和稳定性(流行网站加载成功的程度)。

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。

其他的速度测试工具仅仅是通过发送数据到它们自己的服务器来测量上传和下载的速度。这种数据无法反应用户的体验,因为正常的浏览器通常会频繁的发送一系列的请求(而不是上传或下载一个大文件)到许多的服务器,而不止是一个。

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。

你可以测试任意的翻墙工具,列表之外的也可以。中国的VPN用户也可以测试他们的工具,测试结果也会添加到数据库中。这些数据都将会对所有人开放。实时的在中国测试是非常重要的,因为VPN随时都可能被封锁或解封。我们欢迎任何的关于测试过程的反馈。有技术能力的用户也可以通过审查我们的javascript代码来获悉我们的测试是如何工作的。

我们郑重的邀请翻墙工具的开发者们向我们提供测试过程的反馈。我们的第三个目标是帮助这些开发人员改进他们的产品,让更多的选择适用于中国的顾客。此外,越多的工具可以工作,就意味着中国当局对翻墙的打击就会越难。

中国的用户都知道,在过去的18个月中当局加紧了对翻墙工具的攻击。而翻墙中心将会吹响反击的号角。反其道而行之,让这不再成为秘密。我们要鼓励人们分享翻墙工具可以工作的信息。

我们的第四个目标就是要为GreatFire.org创造收益。目前GreatFire仍然依靠世界各地的热心人士和组织的捐款。我们希望减少对这些机构的依赖,并探寻GreatFire.org自给自足的道路。用户只需到翻墙中心就能购买任意一款我们目前在测试的付费工具。GreatFire将作为这些工具在中国的经销商,因此VPN供应商会给予我们每个零售的一部分。用户也不必在中国购买这些翻墙服务。

星期六, 5月 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?

星期四, 2月 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.

星期四, 9月 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 GreatFire.org 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.

星期三, 9月 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.

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