Sony Pictures Entertainment suffered a major cyberattack on Monday, keeping its computer systems and network down for a second day. Employees at the Culver City-based studio, unable to log onto their computers, resorted to working with pen, paper and landline telephones, according to the L.A. Times. Sources said that other branches of Sony were unaffected by the cyberattack. A known hacker group took responsibility for the hack by leaving a message consisting of a list of threats, a red skeleton and the phrase claiming the hack on employees’ computer screens before Sony Pictures’ system went down.