The Skinners’ Kent Academy and Skinners’ Kent Primary School said they believe the hackers did not have access to student and staff personal records.
But on the academy’s website it still urged parents at the Tunbridge Wells schools to contact their banks to let them know that personal details could have been stolen.
As staff no longer hold vital information on the pupils, including emergency contact details, the decision was taken to close the schools on Monday.
The primary school reopened on Tuesday while The Skinners’ Kent Academy delayed reopening until Thursday so it could ensure all staff laptops and all desktop computers were cleaned.
The school is now teaching remotely for the time being.
A statement sent to the Standard by the Skinner’s Academy Trust which oversees both schools said that they learnt of the attack on June 2.
“Since late February 2021, there has been an increased number of ransomware attacks which have affected education establishments in the UK, including schools, colleges and universities.
“Whilst the Trust had a number of systems in place to prevent such an attack happening on our network, the sophisticated nature of the organisation behind this meant that we could not access essential data and information,” it added.
It continued: “The scale of this attack is significant and staff across the Trust have worked extremely hard to achieve reopening of each site.”
On its website – the school said the hackers told staff what they had access to.
“They do not appear to have access to our School Information Management System (SIMS) which is where we hold all our personal records for pupils, students and staff across the Trust. However, they have encrypted this data so that we no longer have access to it.
“We cannot be sure exactly what the hackers have access to and what they don’t as everything has been encrypted, therefore we are changing all of the trust’s passwords and would recommend that students and parents do the same,” the statement said.