Linux Mint forum users, and anyone who downloaded and installed a copy of the 17.3 Cinnamon edition on Saturday have probably been compromised by hackers and need to take action immediately, the distro's creator has warned.

Clem Lefebvre, confirmed in a blog post that the "intrusion" had taken place over the weekend. He said: "Hackers made a modified Linux Mint ISO, with a backdoor in it, and managed to hack our website to point to it."

He added that the resultant malware infection had only affected ISOs downloaded from the Linux Mint site on Saturday, February 20. "As far as we know, the only compromised edition was Linux Mint 17.3 Cinnamon edition," Lefebvre said. However, by Sunday it was a different story, with Linux Mint confirming that its forums database had also been targeted in the hack of its systems.

Forum users, who have an account on forums.linuxmint.com, were told to change their passwords on all sensitive websites without delay.

Meanwhile, anyone who downloaded the 17.3 Cinnamon edition of the Ubuntu-based Linux distro on Saturday can find out if their computer has been compromised by checking the MD5 signature on the ISO file to see if it matches with the valid versions:

6e7f7e03500747c6c3bfece2c9c8394f linuxmint-17.3-cinnamon-32bit.iso

e71a2aad8b58605e906dbea444dc4983 linuxmint-17.3-cinnamon-64bit.iso

30fef1aa1134c5f3778c77c4417f7238 linuxmint-17.3-cinnamon-nocodecs-32bit.iso

3406350a87c201cdca0927b1bc7c2ccd linuxmint-17.3-cinnamon-nocodecs-64bit.iso

df38af96e99726bb0a1ef3e5cd47563d linuxmint-17.3-cinnamon-oem-64bit.iso

Lefebvre urged users to bin any ISO that was found to have been infected by the hack. He also recommended a re-installation of the OS, and a change of passwords on all "sensitive websites".

Linux Mint took its server offline to fix the issue. The distro added that the hacked ISOs, and the backdoor both led to a location in Bulgaria.

"What we don’t know is the motivation behind this attack. If more efforts are made to attack our project and if the goal is to hurt us, we’ll get in touch with authorities and security firms to confront the people behind this," said Lefebvre.