Guwahati: Oil India Limited's field headquarters in Assam's Dibrugarh district is facing one of the biggest IT crises as a section of the desktop computers have been shut down after malwares were found in them. The company has filed a case with the Assam Police and has claimed the hackers are 75 lakh dollars. "After the preliminary investigation, it came to the notice that OlL's network, server and clients systems are facing network outage. Further, it also came to their notice that, cyber attacker has demanded 75,00,000 USD as a ransom through a note from an infected system," said Oil India in a statement. Earlier, the company said three to four computers were "infected due to malware". "As a precautionary measure, we had to withdraw many computers system from LAN connection after it has come to the knowledge that three to four computers are infected due to the virus and malwares.