A flaw in the Mac operating system is being exploited by hackers, giving them control of thousands of Apple computers around the world.

More than 17,000 Macs, 1200 of which are in the UK, have been infiltrated by the malware dubbed “Mac.BackDoor.iWorm.”

The programme gives the hacker remote access to the infected computer through a complicated communication system that manipulates the search and comment functions of the popular website Reddit.

When a Mac is infected with the iWorm it makes a connection to a command server, Russian security company Dr Web has discovered.

A map of where in the world iWorm infected computers are (Dr Web)

It then uses Reddit’s search function to locate comments posted by hackers in a thread devoted to the discussion of the building-block game Minecraft.

After finding the comments, the malware attempts to connect to the server addresses listed in the Minecraft subreddit, and once connected, the hackers can enter commands to their "botnet" of infected computers.

Botnets are designed to send spam emails, mine for Bitcoin, or direct so much traffic to a website that it crashes.

The method used by iWorm hackers

The compromised computers don’t appear to have used for an attack yet, according to Business Insider, so it’s likely that the iWorm network is still growing.