Various websites associated to the World Cup have been struck by a distributed denial of service (DDoS) attack ahead of the tournament's opening match on Thursday.
The official government World Cup website has been down for more than a day, as well as the websites of some host states. Hacking collective Anonymous has claimed responsibility for the attacks.
The hacker group has published a list of over 60 websites that have successfully taken down and are still offline at the time of writing, including as the Brazil website of recording giant Universal Music.
Public figures that are perceived by the hackers as supportive of the government and the World Cup are also being targeted. Various performers such as Caetano Veloso, Mariana Aydar, and Filipe Catto have had the content of their websites replaced by anti-FIFA messages or taken down.
Last month, the internal communications system of the Brazilian Ministry of External Relations was also hacked, with a possible leak of confidential information.
Even though Anonymous has not claimed direct responsibility for the attack, it has released a YouTube video justifying it and citing general dissatisfaction with the World Cup.
Back in February, the hackers said they were preparing for a string of cyberattacks to FIFA and sponsor websites during the World Cup, including DDoS attacks, as well as website defacement and data theft.
The Anonymous group has vowed to continue the attacks and is posting regular updates on Twitter under the hashtags #OpHackingCup and #OpWorldCup.