Hackers around the world have been deploying malicious software that locks computers until the users pay a ransom. But now one cybersecurity expert has found a new kind of malware that appears to hijack computer data and disable it forever.

The Power Worm is a type of computer virus that security experts have been tracking for awhile, according to the BBC. But this new variant of the bug differs from past versions, in that its code destroys keys that can undo the damage that the virus inflicts.

Security researcher Nathan Scott exposed the malware earlier this week, and noted that it appears to be the result of a coding error made by a hacker who attempted to update the Power Worm virus. Typically the Power Worm infects Microsoft Word or Excel files, but the new variant also goes after other file types.

The virus also typically creates a key that unlocks file encryption. This allows hackers to hold machines hostage while they demand a ransom to unlock the encrypted files.

Scott believes the hacker mistakenly changed the encryption process, leaving no unscrambling key and thus creating a bug that locks files forever.

Another malware researcher suggested that the only option for those infected with the virus is to try to restore their systems from backup files. He noted that if hackers demand a ransom, users should not pay, as their files will not be restored even if they do assent.

Another recent malware variant targets Linux users. Called Linux.encoder, the bug infects websites via add-ons such as shopping systems. The virus then encrypts files, images, pages or scripts and leaves behind a text file detailing the terms for paying a ransom.

One cybersecurity expert noted that encryption ransomware is becoming more common especially as hackers are finding other scams, like stolen credit cards, less profitable. Recent security research has found that Crypto Wall and its variant viruses have already brought the hackers who developed the ransomware around $325 million.