In a statement, Bitdefender's Threat Research director Bogdan Botezatu said: "Since the demise of GandCrab, players in the ransomware space have been fighting for supremacy and affiliates. DarkSide is one such competitor, and although it is relatively new, it has already successfully managed to infect multiple targets and stay relevant.
"The decryptor Bitdefender has released works on all infections to date and helps victims safely get their data back."
As the menace of Windows ransomware has continued to grow over the years, a number of security firms and public groups have come together to release free decryptors for those who have been affected.
"Bitdefender is proud to continue giving back to the cyber security community by helping stop the spread of ransomware.
"Its researchers have been working on ransomware decryption tools for nearly half a decade in collaboration with law enforcement agencies and through NoMoreRansom, an alliance between cyber security vendors and law enforcement. Through the NoMoreRansom initiative, Bitdefender decryption tools alone account for 12 percent of the estimated $632 million in ransoms stopped."
The group behind DarkSide claimed that the decryption key had been created by Bitdefender using a private key that the firm had purchased from the group.
"Bitdefender has released a utility that can decrypt some of our Windows lockers. Linux decryption is impossible," the group said in a statement on its website. "The problem was in generating private keys in Linux. There are no encryption vulnerabilities or other problems in the locker."