A hitherto unknown group that has been dubbed Tortoiseshell is using both customised and common Windows malware to target IT providers in Saudi Arabia, the American security firm Symantec claims, adding that these attacks appear to be focused on the supply chain and ultimately aimed at the providers' customers.

Industrial security intelligence provider Dragos has issued a warning about a threat group it has baptised Xenotime, which it says has expanded its field of operations from the oil and gas industry to now also target electricity utilities in the US.

Security company FireEye says it has been responding to a second attack by the group behind the Triton malware which was used to attack the Saudi Arabian oil company Saudi Aramco last year.