Cambridge Analytica researcher blasts Facebook

Aleksandr Kogan, the app developer at the center of Facebook's data privacy scandal, says he isn't sure whether he ever read the social network's developer policy, which prohibited apps like his from selling or licensing Facebook data to marketing firms.

Kogan tells 60 Minutes in a report to be aired Sunday that he harvested the data of tens of millions of Facebook users, he didn't think obtaining it for a political consulting firm like his Cambridge Analytica was against the rules.

"The belief in Silicon Valley and certainly our belief... was that the general public must be aware that their data is being sold and shared and used to advertise to them," Kogan tells CBS' Lesley Stahl Kogan now says he believes his assumptions were misguided and that what he did in 2014 "was not right and was not wise."

In response to Kogan's interview, Cambridge Analytica issued a response Sunday stating that Kogan and his GSR company made a contractual commitment that the data was compliant with data protection legislation, and that the license was only for up to 30 million respondents in the US. Cambridge Analytica also knocked the quality of Kogan's data, stating that they instead began collecting data on their own in 2015 from willing participants.

"Cambridge Analytica's research showed that the personality types licensed by GSR/Kogan underperformed compared to more traditional ways of grouping people by demographics," the firm said in its statement. Cambridge Analytica re-emphasized its claim that the raw data they received was deleted after Facebook reached out, along with derivatives of the data in its system.

Cambridge Analytica is at the heart of a scandal that's stirred up two national governments and the world's largest social network. Facebook banned the UK-based political data analysis firm last month, saying it had improperly received as many as 87 million user profiles leaked from its service.

Facebook has said that Kogan, a Cambridge University lecturer, collected the data legitimately through a personality quiz app but then violated Facebook's terms by sharing the information with Cambridge Analytica, which was later hired by the Trump campaign during the 2016 US presidential election. In the Sunday statement, Cambridge Analytica said the data used during Trump's campaign was provided by the Republican National Committee.

Facebook learned of the data infraction in 2015 but didn't inform the public. Instead, the company demanded that all the parties involved destroy the information. Recent reports say the data hasn't been completely deleted.

Cambridge Analytica has repeatedly said it obtained the data through a legal license with the company that gathered it.