Ongoing investigation by the Kolkata Police Detective Service has revealed that hackers have been flying around ₹2 crore of at least 10 unsupervised automated teller machines (ATMs) in the city between May 14-22 by intercepting the two-way encrypted messaging and data system that connects an ATM to a bank’s main server, a the police said.

Hackers have stolen anything in between ₹2 to 20 lakh of each machine using a technology experts call “man in the middle” (MITM) hacking. The targeted ATMs belong to the same private bank. The machines’ software has not been upgraded, investigators said.

Two of the hackers, suspected of being part of a gang that carried out a similar operation in Faridabad in the Delhi / NCR region two months ago, were caught on camera by a security camera installed near the hacked cash machines in Kolkata.

“We are in contact with the Faridabad police,” said Murlidhar Sharma, co-commissioner of police (crime). “Account holders haven’t lost anything. The loss was suffered by the company which loads money into these machines, ”Sharma added.

Kolkata police opened the investigation when the bank filed complaints that three ATMs were hacked between May 14-22 and ₹39.6 lakh were stolen several times.

While investigating the case, police discovered that none of the machines in the areas of New Market, Jadavpur and Cossipore police stations had been forcibly broken. The investigation showed that more machines located in Beniapukur, Behala, Phoolbagan and Bowbazar were also hacked during the same period and the amount of money stolen was around ₹2 crores.

Hackers, apparently, took about 15 minutes to hack into the system at each ATM. They had money distributed to ATMs by connecting to the bank’s server using a device that would be connected to cables from the ATM, Sharma said.