Central cyber agencies have encountered a significant challenge in the form of hoax bomb calls, which have delayed over 90 flights in the past week.
A top-level official said the agencies could not trace the actual Internet Protocol (IP) address from which the threats were issued.
Further, officials in the electronic investigation have declared that the accused are not the same case every time. At one point, a note written on tissue paper was found on a Udaipur-Mumbai flight.
In other cases, threats were generated through electronic means. In some cases, the threat was made through social networking sites and, in others, through emails.
According to the preliminary inquiry, the IP addresses had been traced to European countries, but since suspected VPN chaining was developed, tracing had nearly become impossible.
Indian agencies are trying to get details from VPN companies, and their response is awaited.
“Earlier, such threats came in emails and messages exchanged via VPNs. Upon tracing the IP address, we found it belonged to a European nation.
However, it is suspected that VPN chaining has occurred wherein threat emails and messages have been coordinated with technical experts or the sender is technically sound,” said an official associated with the digital investigation process.
India officials further said that if it had been a simple VPN, the Indian agencies would have easily tracked it. The official elaborated on the concept of VPN chaining, where data transmitted through the primary VPN server decrypts and then encrypts and sends it to a secondary VPN server to encrypt and decrypt it once again.
“There has been no significant development on the emails to schools this year mainly because VPN companies do not want to disclose information,” said the official.
It seems that the same encryption technique was applied in these emails. He added that it is difficult for the agencies to pinpoint the actual IP address that will lead to the sender’s location.
As many as 25 flights of Indian airlines received bomb threats on Sunday, causing hardships to hundreds of passengers and forcing authorities to move scores of planes to isolation bays at airports concerned for detailed checks.
