"WE HAVE JOY WE HAVE FUN, WE HAVE MESSED UP MURDOCH'S SUN," LulzSec tweeted late on Monday.
Members of the two groups then began tweeting the login information of former employees of News Corp., including that of Rebekah Brooks, who recently resigned her post as chief executive of News International, the British division of News. Corp.
LulzSec also redirected the Sun and News International's websites to its Twitter feed.
The hacking attack on News Corp. comes a day before Murdoch is set to appear before the British Parliament to be questioned about phone hackings conducted by employees of his News of the World tabloid. The scandal has resulted in the resignations of many high-ranking officials in Murdoch's company and British law enforcement.
LulzSec's return was unexpected as the group announced its retirement three weeks ago, after 50 days of hacking.