NORTH KOREA made no secret of its delight when hackers attacked Sony Pictures Entertainment, the studio behind “The Interview”, a film that lampoons Kim Jong Un, the world’s youngest and worst head of state. The regime’s propaganda arm crowed that a blow had been struck against the “ill-famed cesspool of injustice” [ie, America], and added that North Korea “highly estimates the righteous action taken by the “Guardians of Peace” [as the hackers styled themselves], though it is not aware of their residence.”

The hack was ferocious. The assailants used malicious software that destroyed some of Sony’s systems and let them grab and publish reams of sensitive data such as employees’ Social Security numbers and producers’ intemperate e-mails. (In one leaked e-mail a Sony employee calls Angelina Jolie, a star, “a minimally talented spoilt brat”. He probably wouldn’t have said that to her face.) The hackers also threatened violence against cinema chains that screened the film, which includes a scene in which the youthful North Korean god-king’s head explodes (see picture).

America’s cyber-gumshoes quickly accused Pyongyang of being behind the assault—a charge Mr Kim’s courtiers have denied. The FBI says some lines of code the hackers employed are similar to ones used by North Korean hackers in the past, and notes that internet addresses “associated with known North Korean infrastructure” were used in the attack.

But savvy hackers from elsewhere could have used these to trick investigators into blaming North Korea. “It’s not difficult to send someone down the wrong path,” says Howard Schmidt, a former Obama administration official who advises companies on cyber-security. Code from previous hacks sometimes leaks online, allowing people to copy it. And cyber-criminals often use internet addresses associated with other hackers to try to throw sleuths off their scent.

Security researchers have pointed to more reasons why the North Korean regime may be innocent (of the hack, though not of jailing children for having suspected dissidents for parents). In their initial e-mail to Sony, the hackers asked for money but did not mention “The Interview”. They only latched on to the film after journalists wondered out loud about a possible link between the hack and the satire. Marc Rogers of CloudFlare, a web-security firm, writes that the attackers had a deep knowledge of Sony’s systems and their e-mails seemed to be written by an English-speaker deliberately pretending to be bad at writing the language. He thinks a disgruntled current or former Sony employee could be behind the attack.

The FBI says it has additional information from “sensitive sources and methods” that points to North Korea. But in the absence of more detail, it is hard to be sure. Officials were undoubtedly under pressure to find someone to blame, quickly.

Deciding how to respond to North Korea’s alleged involvement has posed a strategic challenge. Mr Obama has publicly promised a proportional response to what he has referred to as an act of “cyber-vandalism”. It is unlikely to be a coincidence that North Korea has suffered internet outages recently, including one that occurred soon after a North Korean spokesman accused Mr Obama of being “reckless in words and deeds like a monkey in a tropical forest”. The risk is that this could provoke reprisals. America’s heavy reliance on the internet means it is especially vulnerable to online attacks.

According to the New York Times, America has asked China, which is a conduit for much of North Korea’s internet traffic, to rein in Mr Kim’s hackers. Such diplomacy is worth a try, but America’s cause will not have been helped by its decision in May 2014 to indict several Chinese soldiers in absentia for their alleged involvement in hacking the systems of American private companies.

Mission Kimpossible

The Sony saga has highlighted the tensions that can arise between corporate interests and national ones. As the hackers escalated their attack, the studio at first decided to pull “The Interview” from distribution. Such a surrender would have invited every group that didn’t like the way it was portrayed on film to hack a Hollywood studio. After Mr Obama publicly criticised Sony Pictures for failing to stand up for freedom of speech, the firm agreed to distribute the film to a limited number of cinemas and to make it available online. (It promptly became a big digital hit.)

The Tinseltown hack may at last encourage Congress to make it easier for companies to share information about cyber-threats with the government and each other, making it easier to thwart hackers. Previous attempts to get such legislation passed have been stymied by legitimate concerns about privacy. A law that carefully protects people’s personal data, while at the same time removing legal hurdles that still hamper some intelligence-sharing, is badly needed. If one emerges in 2015, perhaps the hackers who hit Sony should get a mention in the credits.