A forensics team has stunned banks and security analysts by highlighting how cash machines can be compromised by insiders (Image: Rubberball / Getty)

“SKULDUGGERY,” says Andrew Henwood, “is a very good word to describe what this extremely advanced, cleverly written malware gets up to. We’ve never seen anything like it.”

What he has discovered is a devious piece of criminal coding that has been quietly at work in a clutch of cash machines at banks in Russia and Ukraine. It allows a gang member to walk up to an ATM, insert a “trigger” card, and use the machine’s receipt printer …