From en.secnews.gr
The attack was first reported by Cyberwarzone.com. He takes advantage of some vulnerabilities, which could have been used for more serious attacks, but in this case the incident was not very complicated and fortunately the impact was small.
The PDF files were uploaded by one hacker using the name online m1gh7yh4ck3r. In recent days, the hacker has uploaded files in official sites of UNESCO, the WHO, the Georgia Tech Institute and a Cuban government site.