Life is slowly returning to normal for Sony Pictures Entertainment after a computer attack that crippled the studio early last week.
Some computer systems crucial to Sony's business operations were finally back online, while employee email access was expected to be back up later in the day, according to people familiar with the situation who were not authorized to comment publicly.
The Culver City unit behind movies such as "The Amazing Spider-Man" is still reeling from the Nov. 24 computer breach that left thousands of employees performing their jobs with pens, paper and fax machines.
"Sony Pictures continues to work through issues related to what was clearly a cyberattack last week," the studio said in a statement. "The company has restored a number of important services to ensure ongoing business continuity and is working closely with law enforcement officials to investigate the matter."
The company has been scrambling to repair the damage to its computer system after a hack by a group calling itself Guardians of Peace. Compounding the company's woes, the attack also seems to have resulted in the pirating of DVD copies of at least five new and upcoming movies. The films began appearing on file-sharing websites just days after the infiltration.
Among the stolen films are the Brad Pitt World War II drama "Fury," which is still in theaters, and the upcoming remake of the musical "Annie." "Still Alice," "Mr. Turner" and "To Write Love on Her Arms" have also surfaced recently on websites.
Sony executives have declined to comment on the scale of the attack, but Internet security experts said it exposed the company's lax computer defenses.
"This is an epic fail on the part of Sony," said Stu Sjouwerman, chief executive of the cybersecurity training company KnowBe4. "They haven't stepped to a level of protection they should have."
Of the leaked Sony movies, "Annie," scheduled for a Dec. 19 premiere in the U.S., is the biggest that has not yet been released. According to the website TorrentFreak, "Fury" is by far the most popular among file-sharers.
The attack comes just days after the arrest of two people in Britain suspected of stealing and leaking a DVD-quality copy of Lionsgate's "The Expendables 3" before its domestic debut.
The FBI confirmed Monday that it is investigating the matter. Sony has also enlisted Mandiant, a cyberforensics unit of the security firm FireEye, to assist in the search for the hackers.
"The targeting of public- and private-sector computer networks remains a significant threat," said FBI spokeswoman Laura Eimiller in a brief statement. "The FBI will continue to identify, pursue and defeat individuals and groups who pose a threat in cyberspace."
Last week, as Sony workers tried to sign on to their computers, they were greeted with an image of a skeleton accompanied by the text "Hacked By #GOP." The message, which contained multiple threats, appeared to be an attempt to blackmail Sony, warning the company that "secrets" were going to be leaked.
Sony employees were unable to log in to computers or access email, bringing work flow to a crawl. Emails to Sony bounced back with the response, "Our email system is currently experiencing a disruption. Please contact the person you wish to reach via office or mobile phone."
On Friday, the website Re/code said Sony was investigating the possibility that hackers in China working on behalf of North Korea could be responsible. Re/code speculated that the attack may have been in response to Sony's upcoming comedy "The Interview," which stars Seth Rogen and James Franco as a pair of would-be assassins of Kim Jong-un.
North Korea propaganda outlets have promised retaliation against the U.S. if "The Interview" is released. The film, which hits theaters Dec. 25, is not among those that have popped up on file-sharing sites.
This is not be the first time Tokyo-based electronics and entertainment giant Sony Corp., of which the studio is one unit, has been the target of cybercriminals. Its PlayStation Network was the victim of a 2011 hack that stole millions of user accounts from the online gaming service. Also in August, hackers took the network offline with a "denial of service."
Times staff writer Paresh Dave contributed to this report.