Unknown hackers last month targeted leaders of the exiled Uyghur community in a campaign involving Windows spyware, researchers revealed Monday. 

Citizen Lab, a digital rights research group based at the University of Toronto, detailed an espionage campaign against members of the World Uyghur Congress (WUC), an organization that represents the Muslim-minority group, which has for years faced repression, discrimination, surveillance, and hacking from China’s government. 

Google alerted some WUC members to the hacking campaign in mid-March, prompting the members to contact journalists and Citizen Lab’s researchers, the report said.

Citizen Lab investigated and found a targeted phishing email sent to members of WUC, impersonating a trusted contact who sent a Google Drive link for a password-protected compressed file containing a malicious version of a Uyghur language text editor. 

The researchers said the campaign wasn’t particularly sophisticated and didn’t involve zero-day exploits or mercenary spyware, but noted that “the delivery of the malware showed a high level of social engineering, revealing the attackers’ deep understanding of the target community.”