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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Wed, Mar 19, 2014

Bing Bests Baidu Censorship

Abstract

Independent research from Xia Chu has shown that, in addition to non-China content, Bing censors a vast amount of content that is hosted inside China and which is not censored by China-based internet companies like Baidu. After communicating our issues with Microsoft, Bing removed certain censorship rules (kudos to Bing), but much work remains to be done.

We recently called for Microsoft to release its transparency report for Bing (as have others - full disclosure, Rebecca sits on our advisory board).  Microsoft has yet to respond to this request. But Xia’s independent research of Bing’s China censorship policy could be regarded as a de facto transparency report for the search engine.

In this thorough study, the results of which we have verified, Xia examined Bing's SERP (search engine results page) for over 30,000 sensitive and nonsensitive query terms, and launched these queries from both inside and outside of China. Comparing and examining these results, plus querying with special search operators, reveals unprecedented detail on Bing's China filtering practices.

The main findings from Xia’s research include:

  • Bing has a list of “forbidden” terms where no results are shown. 139 such terms have been identified.

  • Bing has a blacklist of websites that it never shows to China users. 329 such websites are identified. (5 have been lifted after our communication with Microsoft.)

Thu, Feb 13, 2014

Setting Bing's Broken Record Straight

We can also now trace complicit Bing Chinese censorship back to 2009 as highlighted by Nicholas Kristof. It looks like Microsoft has indeed changed its censorship mechanism after our research made headlines this week. But Bing is still seriously flawed on two fronts: its algorithm favors pro-Chinese government websites by default on all search terms in simplified Chinese and their front end mistakenly delivers explicit censorship of search results on some search terms for users from all over the world.

Wed, Feb 12, 2014

No error here: Microsoft deploying Chinese censorship on global scale

Microsoft says: “The results themselves are and were unaltered outside of China”. This is simply not true.

Tue, Feb 11, 2014

Bing practicing Chinese censorship globally

Our latest research indicates that Microsoft’s search engine Bing is censoring English and Chinese language search on its home page in order to exclude certain results. We have also noticed that Bing is practicing subtle censorship with search results. In both instances, Bing is filtering out links and stories that the Chinese authorities would deem damaging.

Thu, Jan 23, 2014

Massive blocking of foreign media in China

After Tuesday’s report Leaked Records Reveal Offshore Holdings of China’s Elite by ICIJ, China blocked a number of major newspaper websites. All websites below were blocked after publishing copies of the original report. They're all listed as the publishing partners for “Chinaleaks” stories on ICIJ's website. The Great Firewall rarely blocks non-Chinese websites. Many of them have published the Chinese version of the report which probably explains the unusual development.

Newspaper

Main Language

Article

http://www.icij.org

English

Chinese

http://www.theguardian.com

English

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