Improvements to Lewisham’s IT security after a ransomware attack exposed residents’ financial information has cost the council close to £1.2 million, it has emerged.

In April Lewisham reported there was “unauthorised access to an IT storage portal being used by our digital team for data analysis as part of a homelessness project.”

This saw personal data and financial details for council tax, housing benefit, housing, adult social care, education and planning compromised.

A ransomware attack is when the data on an organisation’s computer is locked by encryption. The targeted organisation is asked to pay a ransom in a virtual currency, such as Bitcoin, in order to release the data.

MORE: Lewisham Council contact police after IT storage portal hacked

Lewisham Council’s head of corporate resources, David Austin, said the breach was the main contributor to the £1.2 million overspend in the council’s technology and change budget.

Speaking at a public accounts committee, he said this “revealed that further work was required and that created additional costs that have had to be covered during the year.”

MORE: '20-woman brawl' outside Mordens Wine Bar raises licence concerns

He said changes in General Data Protection Regulation (GDPR) had also contributed to the overspend.

“GDPR came in May and that information security has created more work relating to this as well to ensure that the systems and applications are working at the relevant standards, and that has cost more than expected,” he said.