The group Anonymous appears to have crashed sites for the Justice Department, Universal Music, and the MPAA — apparently to retaliate for the Justice Department’s effort to close Megaupload. The so-called hacktivist collective claimed responsibility on Twitter. “We are too many for them!” one tweet said. Another said that it’s “the largest attack ever by Anonymous — 5,635 people confirmed” trying to bring down sites. This is the second major incident recently involving Anonymous after The New York Times reported last week that the group disclosed personal information about Time Warner’s Jeff Bewkes and Viacom’s Sumner Redstone — as well as other executives at NBCUniversal, Sony Pictures Entertainment, and Disney — to protest their companies’ support for two anti-piracy bills: the Senate’s Protect IP Act and the House’s Stop Online Piracy Act.