The Chinese social media app WeChat is surveilling international users’ messages and using the data collected to tighten censorship toward its Chinese users, according to a report released Thursday by the University of Toronto’s Citizen Lab.
The researchers found that images and documents shared among non-Chinese users were monitored for sensitive content, tagged, and then blocked from being sent to Chinese users. The report says this surveillance helped train the algorithms used by WeChat to block sensitive content in China.
Censorship on Chinese social media is nothing new. In March, the Citizen Lab released a report showing messages referring to COVID-19 were blocked from certain Chinese social media platforms.
However, Jeffrey Knockel, a research associate and one of the study’s authors, said what makes this case distinctive is that international users are becoming unwitting agents of domestic Chinese politics.
“One different demographic of users is being surveilled in order to train the political censorship of another demographic,” Knockel said.
WeChat censors images and documents by assigning these messages a “hash” code or digital signature. The platform keeps a list of banned hash codes, and blocks any messages that match this list. By surveilling conversations among non-Chinese users, WeChat can grow its list of banned hash codes to strengthen its censorship at home.
To test how WeChat monitors its non-Chinese users, researchers took previously banned content and tweaked it to generate a clean digital signature not on the banned list.
They then sent the content to a group of non-Chinese users, waited and then repeated the experiment for a group of Chinese users. They found the “new” content was always banned after it had circulated through the non-Chinese group.
The report then looked at the privacy policies for both the Chinese and international versions of the app for any disclosure that user data was being treated this way. They came up empty.
In response to an inquiry Thursday by the IFCN, a spokesperson for Tencent said:
“We received the Citizen Lab report and take it seriously. However, with regard to the suggestion that we engage in content surveillance of international users, we can confirm that all content shared among international users of WeChat is private. As a publicly listed global company we hold ourselves to the highest standards, and our policies and procedures comply with all laws and regulations in each country in which we operate. User privacy and data security are core values at Tencent, and we look forward to continuing to sustain user trust and delivering great user experiences.”
WeChat is the third most popular messaging app worldwide behind Facebook Messenger and WhatsApp. It boasts a monthly active user base of 1.16 billion users although it’s unclear how many are outside China. A report from September 2019 found WeChat has 1.46 million users in the United States.
Knockel said it’s important for WeChat users to know their data is being used in this way. He said users should decide whether they’re comfortable with WeChat’s monitoring and actions
“If you are comfortable being under that kind of surveillance, perhaps you find discomfort in contributing to the censorship of another demographic of people,” Knockel said.
This article was updated to include a statement from a Tencent spokesperson.