A new report by researchers at the Citizen Lab, at the University of Toronto’s Munk School, reveals that popular social media app WeChat surveils all users—even those with accounts registered outside of China—and uses messages from those accounts to train censorship algorithms to be used against China-registered accounts.

To detect the surveillance of non-China-registered accounts, researchers developed and ran two experiments, making use of WeChat’s method of utilizing digital fingerprints for images and documents: a first conversation between only non-China-registered accounts for triggering surveillance and a second conversation containing a China-registered account to measure changes in censorship. When they sent politically sensitive content (such as an image of human rights activist Liu Xiaobo) in the first conversation, they observed an increase in censorship in the second, revealing that the first conversation was under surveillance despite being among only non-China-registered accounts.

While in previous research non-China-registered accounts had not been found to be under political censorship, the state of surveillance was not known, given that their surveillance did not result in their own censorship or have any other immediately obvious effects. This may have led WeChat users outside of China to think that WeChat’s political censorship and surveillance systems don’t affect them. But this research shows that by using WeChat, not only are the files and images they share under political surveillance, but their content is being used to train and build up the censorship system that WeChat uses to censor China-registered users.

“Some international users of WeChat may be uncomfortable with their communications being under political surveillance. Others may be comfortable bearing that themselves, but find discomfort in knowing their communications contribute to the political censorship of others.”– Jeffrey Knockel, Post-doctoral Fellow

Researchers also analyzed WeChat’s public-facing policy documents, made personal data access requests, and sent detailed questions to Tencent data protection representatives. They used these methods to assess if WeChat could reveal or explain the surveillance practices they detected and whether WeChat representatives would explain the company’s practices when directly asked about them. None of these methods provided a clear rationale or description of the surveillance that researchers detected in the course of the experiments.

Citizen Lab put together a supplementary document that provides a summary of the research findings and questions and answers from the research team.

Read the full report.
Read the summary and FAQs.

Follow this report in the news

WeChat surveils international accounts to decide what to censor for Chinese users, study says (South China Morning Post)
China’s WeChat Monitors Foreign Users to Refine Censorship at Home (Washington Post)
WeChat’s surveillance of international users boosts censorship in China, researchers say (CBC)
Tencent surveils foreign accounts to aid domestic censorship (Financial Times)