Hackers collective Anonymous, which had gone underground for the past few months, reared its deadly head again Thursday, and shut down the Department of Justice (DOJ), the Motion Picture Association of America (MPAA), Recording Industry Association of America (RIAA) and the Universal Music Web sites via The distributed denial of service (DDoS) attacks, in retaliation against the U.S. government crackdown on Megaupload and Megavideo sites.

After DOJ announced that ICE, a federal group, had shut down Megaupload and Megavideo sites and seven individuals and two corporations were indicted for copyright infringement and could face up to 50 years in prison, Anonymous struck back shutting down the Web sites operated by the bigwigs.

Recording Industry Association of America—Department of Justice—Universal Music—all TT, all TANGO DOWN, Anonymous tweeted. Get some popcorn… it's going to be a long lulzy night.

Anonymous also tweeted, for #SOPA supporters their#SOPAblackout is today, indicating that it was their way of protesting against SOPA (the Stop Online Piracy Act), a draconian anti-piracy bill which is currently under debate in the U.S. Congress. Many Web giants such as Google, Wikipedia and Reddit protested on Wednesday against SOPA by staging a blackout, either partial or total.

MPAA, RIAA and Universal Music are supporters of SOPA.

At the time of reporting, Universal Music website said The site is under maintenance. Please expect it to be back shortly. MPAA was up and running. But www.riaa.com, www.justice.gov and www.copyright.gov sites were down and out for the count.

The action of Anonymous is a big blow to these organizations and the group itself said this is the Largest On Scale Attack Ever.