Researchers said Monday that unknown hackers used Windows spyware to target representatives of the exiled Uyghur minority last month.

The World Uyghur Congress (WUC), an organization which advocates for the Muslim minority group that has long been subject to repression, secernment, surveillance, and hacking by China’s government, was the target of an espionage campaign, according to Citizen Lab, an online liberties research group centered at the University of Toronto.

According to the post on X, some WUC members contacted journalists and researchers from Citizen Lab when Google informed them about the hacking campaign in mid-March.

After conducting an investigation, Citizen Lab discovered that a targeted phishing email was sent to WUC members, posing as a reliable source and carrying a Google Drive link to a password-protected packed file that contained a malicious installation of a text editor in the Uyghur language.

Zero-day attacks and mercenaries spywares were not used in the campaign, according to the researchers, who also pointed out that “the delivery of the malware showed a high level of social engineering, revealing the attackers’ deep understanding of the target community.