It's said security company vpnMentor found names, financial information and civil data - including official government ID numbers, work records and phone numbers - for around 17 million people, which includes 6.7 million children.
The country's computer emergency security team has now restricted access to the server, while pvnMentor has revealed the extent of the leak.
The firm's Noam Rotem and Ran Locar wrote: "The data breach involves a large amount of sensitive personally identifiable information at the individual level...
"This data breach is particularly serious simply because of how much information was revealed about each individual."
According to the researchers, the cache of information contained 18gb of data across files saved to an unsecured server created and ran by marketing and analytics company Novaetrat.
Amongst the personal data was also financial records with account balances of one large Ecuadorean bank, while tax records were also found on another file.