Indian security firm Seqrite Cyber Intelligence Labs claims it discovered the advertisement and then made contact with the hacker.
The Indian Registry for Internet Names and Numbers is governed by the National Internet Exchange of India. Seqrite said it had informed government authorities and the Asia Pacific Network Information Centre about its findings.
The company said in a statement that the entire data dump was being offered for 15 bitcoin (about $80,715). Additionally, the hacker was also offering to take down the networks of organisations whose data was leaked, for the right payment.
After noticing that the email addresses of a prominent Indian technology firm and a government organisation were present in this sample, the researchers asked for a more detailed list of what was up for sale.
A list of approximately 6000 email contacts was then provided by the hacker which confirmed the researchers' suspicions that the national Internet registry had been breached.
The researchers said the seller claimed to be able to tamper with the IP allocation pool, which could result in outages or a denial of service.
"Along with the access, the hacker is also selling credentials, personally identifiable information and various contractual business documents, and claims to have access to a large database from the Asia Pacific Network Information Centre," Seqrite said.