The hacking collective, Anonymous, has exposed the details of almost 1,415 officials who were taking part in the UN Framework Convention on Climate Change (UNFCCC) to protest the arrest of activists before the summit took place.
The website of the summit organisers was hacked and the names, phone numbers, usernames, email addresses, and other details were published on a website. The officials belonged to various nationalities including the UK, Switzerland, Peru, France, and the US.
Oliver Farnan, security researcher at the Cyber Security Network in Oxford University said, "For the UNFCCC itself it's embarrassing. The specific attack that was used [an SQL injection attack] is a well-known vulnerability ... To have their entire user database compromised in this way demonstrates a lack of focus on security."
The researcher said that the measures used by the website to ensure security had been "old and weak hashing algorithm."
He added that the leak can be countered by changing passwords of the accounts reports The Guardian.
Farnan said, "Although it's embarrassing, it's essential to ensure that their users don't get compromised in follow on attacks."
The climate activists had been peacefully marching on Sunday, when a group of miscreants attacked the police throwing bottles which led to the police retaliating. The march had been the first since the 13 November attacks which has put Paris in the state of Emergency.
The protest had taken place at the site of the deadliest attack on 13 November - Place de la Republique; to make sure that the flowers and candles lain for the victims were not disturbed the protestors had maintained a gap.
Anonymous has previously declared war against Isis saying "will hunt you down" by taking down any Twitter accounts related to the Islamist militant group after the Charlie Hebdo attacks, reinforcing their attempts after the Paris attacks.