On November 11, 2015, the Tunisian hacker group Fallaga team successfully hacked and defaced the website for the JSF in North London - Europe's largest Jewish school. The defaced page featured the above message, attacking "Zionist" crimes against Muslims.
Fallaga team are active on Facebook and Twitter, and have participated in multiple ops and cyber-attacks, mainly on Tunisian, French, and Israeli websites. Their Twitter page currently has 985 followers, and they have close to 10,000 Facebook fans.
Source: rt.com, November 11, 2015. Twitter.com/Fallaga_Team; Facebook.com/officiel.Fallaga