GCHQ has warned officials involved in organising the general election that they could be targeted by state-sponsored hackers attempting to disrupt the poll or manipulate the result.
The intelligence agency's National Cyber Security Centre has advised local government workers overseeing voting to take care to avoid giving away information that might be “useful to those who aspire to manipulate or compromise electoral processes in the UK.”
In a briefing issued last week, the NCSC said those seeking to cause “damage” might attempt to identify individuals with pivotal roles, using information on social networking websites, such as Facebook and Twitter. It urged individuals to be “cautious about the detail they provide to others regarding their election duties.”
The advice, drawn up together with the government's Centre for the Protection of National Infrastructure, cited several examples of foreign countries being targeted in recent years. Some were likely to have been "state-sponsored" attacks.
The Cabinet Office has "stood up" an "election cell" which will hold regular meetings over the next five weeks to examine potential security threats.
Examples cited by the NCSC of attacks on the elections of other countries included claims by Ukrainian authorities that attackers targeted election officials during the country's presidential elections in March.
Ukrainian officials were sent "phishing emails" including "malware-infected greetings cards" in an attempt to steal passwords and personal information - with personal details of election officials allegedly bought on the dark web.
The NCSC briefing stated: "Over recent years, there have been reports of cyber attacks, using a variety of techniques, timed to coincide with elections around the world ... It can be difficult to know who is behind a cyber attack, but some of the attacks on other countries are likely to have been state-sponsored. Others probably involve hackers (some of whom may be working for hire), hacktivists or cyber criminals."
The NCSC said that the UK's voting system "does not lend itself to electronic manipulation" because ballots are counted by hand rather than using computers.
But potential threats include "attempts to obtain user names and passwords and other personal information ... Internet-connected databases may also be of interest to attackers."
It warned that hackers could use the email accounts of officials to send out fake communications.
The briefing continued: "There is also a risk that individuals may unintentionally give away information useful to those who aspire to manipulate or compromise electoral processes in the UK.
"Those seeking to cause such damage might attempt to identify people with pivotal roles in the election process using information that’s available online. Therefore, election officials should be cautious about the detail they provide to others regarding their election duties.
"All individuals involved (whether local government employees or those in temporary roles at polling stations, managing postal votes or at the count) have a vital part to play in ensuring confidence in the election process."
The NCSC, which was formed by GCHQ in 2016,urged officials to avoid sharing information about their role in the election online and report anyone "attempting to gain access to parts of the electoral process where they do not have an obvious and legitimate requirement to do so."
The NCSC is also on alert for potential "distributed denial-of-service" (DDoS) attacks, under which attackers could overwhelm government servers in order to make official websites unavailable at key moments, such as shortly before the deadline for voter registration, and polling day, on Dec 12, itself.
Downing Street has been accused of "sitting on" a report by parliament’s Intelligence and Security Committee (ISC) which examines allegations of foreign interference in the 2017 election and 2016 Brexit referendum. No 10 insists the report will be published in "due course".