Sony Pictures Entertainment is investigating the possibility that North Korean hackers were behind the attack that took down the studio’s corporate network this week, Variety has confirmed.

However, SPE currently has no evidence that the hack — which has effectively shut down email and other electronic systems since Monday — was perpetrated by individuals or groups with ties to North Korea, according to a source familiar with the situation. A source said the studio is looking into all possible sources of the hack attack.

In the Nov. 24 attack on the studio’s corporate systems, an image of a skeleton appeared on company computers with a message that said, “Hacked by #GOP,” with the group behind it calling itself “Guardians of Peace.” The message threatened to release “secrets and top secrets” of the company, but it’s not known whether any SPE trade secrets have been divulged since then.

Since the attack, some observers have speculated that the SPE network takedown was somehow related to “The Interview,” the studio’s geopolitical spoof starring James Franco and Seth Rogen (pictured above). In the film, slated for Dec. 25 release, Franco is host of latenight talkshow “Skylark Tonight” and Rogen plays his best friend and producer. When the duo secure an interview with Kim Jong-un, the mysterious and ruthless North Korean dictator, they are approached by the CIA and asked to assassinate the Korean leader.

An SPE rep declined to comment. On Tuesday, the studio released a statement that said: “Sony Pictures Entertainment experienced a system disruption, which we are working diligently to resolve.” Automatically generated responses to emails sent to email addresses at SPE as of Saturday still say, “Our email system is currently experiencing a disruption. Please contact the person you wish to reach via office or mobile phone.”

Sony originally skedded “The Interview” for an Oct. 10 bow before moving the release date to Christmas Day 2014. This summer, an unofficial spokesman for North Korea said the movie “shows the desperation of the U.S. government and American society.”

An analysis of the text of a message from “Guardians of Peace,” which has been posted online, has shown that it’s encoded in a format compatible with Chinese and Korean characters. However, security experts cautioned against reading too much into that, noting that hackers frequently plant misinformation to throw off pursuers.

SPE’s investigation into a North Korean connection to the hack was reported Friday by Recode.