OIL's Manager, Security, Sachin Kumar, who filed an FIR with the police on Tuesday night, said that their server, network, and other related services were affected due to the cyber attack of ransomware on Sunday.
The OIL, however, said that exploration and production work of the company have not been affected due to the suspected cyber-attack.
OIL spokesperson Tridiv Hazarika said that there has been no impact on the production and drilling activities due to the cyber-attack.
"The production and drilling activities are not fully reliant on IT resources. The software which deals the business functions including payments to vendors and contractors also has not been affected and is functioning as usual," Hazarika quoted in media.
Sachin Kumar, in his FIR, said that presently, OIL server, network and other related services are affected.
OIL is a public sector undertaking, and due to this ransomware cyber attack, OIL and the government exchequer has incurred huge financial loss as business through IT has been seriously affected," he mentioned in his complaint to the Police.
Quoting a communication from Deputy General Manager, IT, Keshab Bora, Kumar said that on Sunday a cyber attack of ransomware occurred on one of the work stations of the G & R (Geological and Reservoir) Department.
"After their preliminary investigation, it came to their notice that OlL's network, server and clients PCs are facing network outage. Further, it also came to their notice that, thee cyber attacker has demanded 75,00,000 USD as a ransom through a note from the infected PC," the FIR said.
OIL is India's second largest national 'Navratna' company after ONGC in terms of total proved plus probable oil and natural gas reserves.