A cyber criminal from Colchester has admitted running a product testing service which allowed hackers to see whether their malicious software could beat anti-virus scanners.

Goncalo Esteves, 24, of Cape Close, ran the website reFUD.me, which offered the service to hackers for a fee.

Under the pseudonym KillaMuvz, he also sold custom-made malware-disguising products and offered technical support to users.

He pleaded guilty to two computer misuse offences and a count of money laundering at Blackfriars Crown Court following a joint investigation by the National Crime Agency (NCA) and cyber security firm Trend Micro.

He will be sentenced at Blackfriars Crown Court on Monday, February 12.

Esteves called his encryption tools Cryptex Reborn and Cryptex Lite. Part of a family of cyber tools known as crypters, they could be used by hackers to improve their chances of dodging anti-virus scanners.

He sold them for use in packages which varied in price according to the length of the licence.

A month of Cryptex Lite cost $7.99 ( about £5 at the time of offending) while a lifetime licence for Cryptex Reborn cost $90 (about £60). Esteves provided customer support via a dedicated Skype account and accepted payment either in conventional currency, in the cryptocurrency Bitcoin or in Amazon vouchers.

NCA officers discovered that Esteves made £32,000 from more than 800 Paypal transactions between 2011 and 2015.

Mike Hulett, head of operations at the NCA’s National Cyber Crime Unit, said: “Esteves’s crimes weren’t victimless. His clients were most likely preparing to target businesses and ordinary people with fraud and extortion attempts.

“While offenders like Esteves try hard to stay hidden from law enforcement, NCA officers have the training and technical capability to detect them and put them before the courts.

“This is bolstered by strong partnerships with the private sector. We’re grateful to Trend Micro for their ongoing support in tackling cyber crime.”

Rik Ferguson, Trend Micro vice president of security research, said: “Trend Micro actively works with global law enforcement to assist in the investigation and prosecution of online crime.

“In this particular case the NCA and the justice system have acted against not just a criminal, but a “service provider” to the wider online underground who enabled other criminals’ attacks.

“We hope that this successful prosecution sends a message to the community that online crime is no different from the more traditional kind – it is harmful, it does carry risks and criminals are not invisible.”