I'm not trying to scare you but your Metadata, which summarizes basic information about your data and can make finding and working with particular instances of data easier, is showing and it can lead people to your credit card details straight away.
Companies use the information to market you their products according to your transactions
According to scientists, it’s almost certain to match an anonymous credit card record with some identity by knowing only a few pieces of outside moving information such as a visit to a restaurant, what you bought there, and how much it cost. After they have this information they can track down your credit details by checking the transactions from the data set and matching the inputs with your information that they already have.
The Associated Press stated an example as follows:
“The researchers wrote about looking at data from September 23 and 24 and who went to a bakery one day and a restaurant the other. Searching through the data set, they found there could be only person who fits the bill - they called him Scott. The study said, "and we now know all of his other transactions, such as the fact that he went shopping for shoes and groceries on 23 September, and how much he spent."
At MIT Institute in the US, the computer scientist together with a team examined credit card record of past three months belonging to 1.1 million people. However the records containing personal data including account numbers were stripped the same way as usually companies do in order to sell data of local purchases etc to other companies and organizations.
Big data usage has been a tremendously profitable aspect for the private companies because they are able to fetch in personal data completely about their consumers. Online purchases and browsing activities allows these companies to get a massive wealth data out of you. This data is primarily used for advertising according to specific customer needs and marketing campaigns.
"While government surveillance has been getting a lot of press, and certainly the revelations warrant such scrutiny, a large number of corporations have been quietly expanding their use of data," said privacy consultant and author Rebecca Herold. Studies like this show "how metadata can be used to pinpoint specific individuals. This also raises the question of how such data would be used within insurance actuarial calculations, insurance claims and adjustments, loan and mortgage application considerations, divorce proceedings."
MIT team results were similar to previous experiments including the one performed by Montjoye’s team back in 2013. That was a successful experiment when they managed to get the perfect records matched up to 95 absolute percent.
"We're building this body of evidence showing how hard it actually is to anonymise large sets of data like credit cards, mobile phones, and browsing information," de Montjoye told Aviva Rutkin at New Scientist. "We really need to think about what it means to make data truly anonymous and whether it's even possible.”