NEW DELHI: IT company Wipro receiving an anonymous threat of a toxic drug attack unless it pays Rs 500 crore in bitcoins is part of a criminal trend gathering force all over the world — the bitcoin ransom.Transactions in the virtual currency of bitcoin, which is part of no banking system, cannot be tracked which makes it easier for cyber criminals to run their trade. People can send and receive money online through bitcoins anonymously.While Wipro has been threatened with a toxic drug attack, the more common form of this crime is hackers infecting a computer system with ransomware which encrypts all the data and then demanding payment in bitcoins to unlock the data or devices. A large number of individuals and organisations end up paying ransom to rescue their data.After getting the ransom, hackers send an encryption code which unlocks the data. In some instances, they offer to unlock a small part of the encrypted data to show the victim that the data could be rescued.Experts say bitcoin transactions are on the rise due to a large number of victims of ransomware attacks deciding to pay up instead of reporting the crime.Currently, a bitcoin is worth $1,595. The total value of the bitcoin market is about $24.5 billion, thrice what it was this time last year.According to the US Department of Justice, ransomware attacks have quadrupled this year from a year ago, averaging 4,000 a day. The ransomware payments range from $500 to $30,000, depending on the importance of the data.In February, Hollywood Presbyterian Medical Center in Los Angeles paid $17,000 to get its files unlocked after a ransomware attack. Hackers broke into its servers and encrypted a huge amount of data rendering the documents unreadable, paralysing most of the services in the hospital.In India, ransomware attacks originate mostly from outside the country.Last year in August, computer server of a diagnostic centre in north Delhi was hacked into. Hackers demanded $1,300 ransom in bitcoins. They encrypted all the files and left a message, 'your data is encrypted'.In January this year, a horse-racing website operating from Bengaluru, RacingPulse.in, was hacked and all its filed encrypted. The hackers demanded an unspecified amount in bitcoins as ransom. They said the amount would depend on how fast the website owners got in touch with them. They offered to decrypt a small part of data to prove that they can decrypt all the files after receiving the ransom.Many banks and big corporate houses have suffered ranbsomware attacks in India before the Wipro case.► The biggest prevention against a ransomware attack is to keep a safe and timely backup of all the data. After a ransomware attack, the back-up data will help limit the damage to a great extent.► Tell your staff to be careful about malware. Suspicious emailed links should not be opened.► Get expert help to make your system more secure so that an attack can be detected and foiled at an early stage.