Jewish community organisations have been issued with guidance advising what to do if they are hit by the cyber-attack that brought much of the NHS to a standstill.

The attack, known as ‘ransomware’ because it encrypts files before demanding a payment to retrieve them, has hit more than 200,000 organisations across the world, and this week the Jewish community was told to report any impact to the Community Security Trust (CST) immediately.

“The real-time reporting of such incidents is crucial to our community’s ability to prevent any targeted patterns of cyber-attack,” said a CST spokesman, as a guidance document was issued.

Security chiefs said that while it was virtually impossible to fully guard against attack, “there are many measures that organisations can easily take to protect themselves”. This includes using only genuine licensed software and operating systems, and installing security updates when they become available.

In particular, the CST warned the community to be careful with emails, given that this is a common form of attack. “The attacker sends an email with an attachment or a link within the email,” they said. “Once the link or attachment is clicked on, it enables the attack to begin, often without any visible signs.” Such attacks often come from unknown companies or organisations.