London. ‘Accidental hero’ halts ransomware attack. Expert who stopped spread of attack by activating software’s ‘kill switch’ says criminals will ‘change the code and start again’
The “accidental hero” who halted the global spread of an unprecedented ransomware attack by registering a garbled domain name hidden in the malware has warned the attack could be rebooted.
The ransomware used in Friday’s attack wreaked havoc on organisations including FedEx and Telefónica, as well as the UK’s National Health Service (NHS), where operations were cancelled, X-rays, test results and patient records became unavailable and phones did not work.
But the spread of the attack was brought to a sudden halt when one UK cybersecurity researcher tweeting as @malwaretechblog, with the help of Darien Huss from security firm Proofpoint, found and inadvertently activated a “kill switch” in the malicious software.
The researcher, who identified himself only as MalwareTech, is a 22-year-old from south-west England who works for Kryptos logic, an LA-based threat intelligence company.
“I was out having lunch with a friend and got back about 3pm and saw an influx of news articles about the NHS and various UK organisations being hit,” he told the Guardian. “I had a bit of a look into that and then I found a sample of the malware behind it, and saw that it was connecting out to a specific domain, which was not registered. So I picked it up not knowing what it did at the time.”
The kill switch was hardcoded into the malware in case the creator wanted to stop it spreading. This involved a very long nonsensical domain name that the malware makes a request to – just as if it was looking up any website – and if the request comes back and shows that the domain is live, the kill switch takes effect and the malware stops spreading. The domain cost $10.69 and was immediately registering thousands of connections every second.
MalwareTech explained that he bought the domain because his company tracks botnets, and by registering these domains they can get an insight into how the botnet is spreading. “The intent was to just monitor the spread and see if we could do anything about it later on. But we actually stopped the spread just by registering the domain,” he said. But the following hours were an “emotional rollercoaster”.
