After being warned against using the mailroom to send out private parcels, former Morrison employee, Andrew Skelton, 43, leaked bank and personal data of nearly 100,000 supermarket staff.
The data breach at the company's Bradford head office cost the firm more than £2 million to amend.
Information which included salaries, National Insurance numbers, dates of birth and bank account details of employees were sent to The Guardian, Trinity Mirror and the Bradford Telegraph & Argus last year as well as data sharing websites.
Mr Skelton was disciplined in 2013 after a package was found in the HQ post room. Skelton had been conducting eBay deals using the post room.
The defendant bore a grudge against Morrisons, leading to his offending in this case. A draft resignation letter found by detectives and written by Skelton spoke of his “little concern for the company”.
Skelton of, Liverpool, denies counts of fraud by abuse of position, unauthorised access to data with intent to commit an offence and disclosing personal data. The trial continues.
Todd Partridge, director at Intralinks says, “The consequences of an attack from the inside can be every bit as serious as being hacked from the outside. Research by the Ponemon Institute shows that 51 percent of respondents aren't convinced their organisations have the ability to manage and control user access to sensitive documents and how they are shared.”