Three bank clerks employed by Lloyds Banking Group have been accused of attempting to steal £2 million after installing a remote access device on a colleague's computer.
It is alleged that the accused men made a series of fraudulent transfers totalling £2,036,500 using stolen log-in details, according to the Oxford Mail.
Tai Hulbert-Thomas of Oxford, Neil Bautista of Maidenhead, and Mawli Thurairajah of Harrow, who all stood trial at the Old Bailey this week, deny any wrongdoing.
The bank became aware of fraudulent activity in August 2012, after a branch manager in Slough was notified of a suspicious transaction of £50,000 into a customer's account, the court heard.
This led to an investigation which revealed that a 'USB mouse, keyboard and mass storage' device had been planted on a branch computer.
"The device allowed remote access into the secure banking systems that led to fraudulent transfers being made by the criminal group, causing significant loss to the bank," said Prosecutor James Thacker.
Transfers are believed to have been made between 5.59am and 7.15am, when the branch was closed. Although it is claimed that attempts were made to take £2 million, the bank is believed to have lost £400,000.
However, customers were not affected by the alleged fraud.
In an email statement to ComputerworldUK, a Lloyds Banking Group spokesperson highlighted the bank's investment in security and anti-fraud systems.
"We take the financial security of our customers extremely seriously and have advanced safeguards in place across our IT systems. We have been supporting the Police throughout their investigation - we are unable to comment further at this time."
According to security expert Graham Cluley, the case bears a resemblance to attempts to defraud Barclays and Santander last year. These involved using a small KVM (keyboard-video-mouse) device attached to a 3G router and placed on the back of a branch computer, making it hard for a bank's security team to detect.
"It is like having key-logging malware on your computer, which is fairly common, but it is not software, it is hardware doing this," said Cluley. "As a result there is nothing for antivirus software to find on your computer.
"Some of these USB key-loggers are as small as your thumbnail, they can be plugged in the back of your computer, and you may not realise that they are there at all. It is often a complete cobweb of wires behind a computer, and people may not know what all the wires are for."
He said that while it is difficult for a company to prevent such an attack, a combination of physical controls and fraud detection systems can help react quickly.
"The general advice to companies is to keep a close eye on who does what to your computers, and who has physical access," Cluley said. "You also need a regular audit as to what is plugged in where.
"There is technology which put in place to control access to USB ports, and to warn and block if something unauthorised is plugged in, but that is not always simple.
"Ultimately it comes down to vigilance, although you would expect that a bank would notice unusual transactions of particularly large sums. They are good at looking at the movement of money and data and questioning unauthorised transactions, particularly if they are done outside of office hours."