These hackers are working for the Chinese government and have broken into telecoms networks to track Uighur travellers in Central and Southeast Asia, two intelligence officials and two security consultants who probed the attacks.
These intrusions are part of a wider cyber-espionage campaign targeting "high-value individuals" such as diplomats and foreign military personnel, the sources said. But China has also prioritised tracking the movements of ethnic Uighurs.
As part of the campaign, different groups of Chinese hackers have compromised telecoms operators in countries including Turkey, Kazakhstan, India, Thailand and Malaysia, the four sources said. Those countries are frequently used as transit routes by Uighurs to travel between Xinjiang and Turkey in what rights activists say is an attempt to escape state persecution. Beijing has said that such travellers may be going to fight for militant groups in Iraq and Syria.