Chinese news sites have been infected in a bid to compromise dissidents in the country, according to security firm FireEye.
The so-called watering hole attack infected news sites popular with targets. When dissidents vist the site, they would be infected with malware.
The attack used an Internet Explorer 8 vulnerability patched this month, researchers Thoufique Haq and Yasir Khalid said, adding the bug would likely be rolled into other exploits.
"This is clearly a targeted attack on a very narrow portion of the Chinese populous," they said.
"However, since cyber attackers are quick copycats, we expect this exploit to be replicated quickly."
They said the attack resembled a watering hole attack launched late last year against the website for the policy think tank Council on Foreign Relations, the influential membership group that helps shape USforeign policy.
The malware was delivered to users whose operating system language was set to English, Chinese, Japanese, Korean or Russian.