Hackney Council has asked registered postal voters to reapply ahead of local elections in May following the disruption caused by a cyber attack last year.
The east London authority said there is no evidence that any postal voting data was stolen during the attack in October, but residents have been asked to reapply so their votes can be verified.
Affected voters can still cast their ballot in person, but without submitting a new application will not be able to vote by post in May – something the council is encouraging all voters to do because of the ongoing coronavirus pandemic.
Cyber criminals breached the council’s systems last year and the London borough confirmed that part of its elections computer system was damaged in the attack.
Do you normally vote by post?
You must register again for a postal vote in advance of May's elections, and you'll receive a letter and form from us in the next few days.
More information on how a serious cyberattack has affected our systems 👇https://t.co/UyoybARTJy
— Hackney Council (@hackneycouncil) January 21, 2021
Earlier this month, the council said data stolen in the attack had been published to the dark web, with experts confirming a limited set of data had been put online but was not on a widely available on a public forum or visible through internet search engines.
The local authority also said it appears at this stage that the vast majority of sensitive or personal information it holds has been unaffected.
Hackney Council chief executive and electoral registration officer Tim Shields said: “I’m really sorry for the additional disruption that this attack by organised criminals is continuing to cause residents – and I share their anger and frustration.
“I know that many people may be concerned about their personal data, but there is no evidence to suggest that their postal vote registration data has been stolen or published online.
“Due to coronavirus, voting will be different this year, and we are encouraging as many people as possible to register to vote by post to reduce pressure on polling stations and the social distancing we will need to follow to help keep everyone safe.”
The National Cyber Security Centre (NCSC), National Crime Agency (NCA), Information Commissioner’s Office (ICO) and the Metropolitan Police are all working with the council in response to the incident.