A group of hackers is threatening to take the gaming networks related to Xbox and PlayStation consoles offline for a week during Christmas, mirroring a similar attack last year that stopped gamers around the world from accessing games.

The group, which calls itself Phantom Squad, says it has already started attacking various gaming networks, including PlayStation Network, Xbox Live and Grand Theft Auto 5, and on Tuesday morning it said it had taken Reddit offline with a cyberattack. Experts have contacted Reddit to ask if it went offline as a result of a cyberattack, but at the time of publication there has been no response.

Sony's PlayStation 4 – the hottest-selling gaming console in the United States – has been in the market for a while now, and since its release, hackers have been tinkering with it to find a way to run unauthorized software.

Though breaking the protection on PlayStation 4 is a huge deal, a hacker who calls himself CTurt has claimed to develop a fully jailbroken version of the PlayStation 4 with the help of a kernel exploit that he previously created. The current jailbreak allows dumping of the system RAM from other processes and installing custom firmware that can be used to run homebrew applications that aren't approved by Sony. There is still a few other security issues to get by.

The cyber-assaults disabling Sony PlayStation and Microsoft's Xbox game consoles may have been done by hackers 'for laughs' - but is something more sinister going on?

​Every week, Ann and Jim Johnson put away a few pounds in their Christmas club. Their younger daughter got a doll’s house, their middle son a bike. But their oldest, Jamie, got a Sony PlayStation 4 – followed by several hours of anguished, then tearful, failure to make it work properly. He wanted to play with his friends and he couldn’t. It was the second disastrous cyberassault on Sony in a month.