Linux sysadmins are being specifically targeted by hackers demanding one Bitcoin to gain access to their own data.

Usually, it's Windows systems that get hit by ransomware, but a new strain targets Linux systems to extort cash.

"Judging from the directories in which the Trojan encrypts files, one can draw a conclusion that the main target of cybercriminals is website administrators whose machines have web servers deployed," said Russian antivirus firm Dr Web in an advisory.

Dubbed Linux.Encoder.1, the software sorts through files on a target system and encrypts all files in the home, root, MySQL, Apache, and Nginx directories using 128-bit AES.

It then goes through the rest of the system data and encrypts the contents of directories with the following strings in their names: public_html, www, webapp, backup, .git, and .svn. For each directory, the trojan writes the file README_FOR_DECRYPT.txt to disk, which carries the attacker's demands.

"To obtain the private key and php script for this computer, which will automatically decrypt files, you need to pay one Bitcoin(s) (~420 USD)," the message reads. "Without this key, you will never be able to get your original files back."

The actual value of a Bitcoin is currently around $380 (it was $420 early last week) but that's unlikely to be much consolation to afflicted users who may have little choice other than to pay up if they haven't backed up their data. If they have, it still means the system needs to be wiped and everything re-installed.

The new malware has its weaknesses – it requires admin level access to run – but Dr Web warns that the code is spreading at the moment using a critical flaw in the CMS Magento. A patch was released for this on October 31, but with just over a week gone, many systems may still have the flaw that would allow Linux.Encoder.1 room to operate. ®