Foreign states such as Russia and China could have tampered with a voter registration site in the run-up to Britain's EU referendum last year, according to a report by U.K. lawmakers.
The report, published Wednesday by the Commons Public Administration and Constitutional Affairs Committee (PCAC), said members of Parliament were "deeply concerned" regarding the allegations of foreign interference in last year's Brexit vote.
The U.K. government's official "register to vote" site crashed on June 7 last year, just before the deadline passed for tens of thousands of voters to sign up, and members of Parliament on the PCAC said a foreign cyber attack could not be ruled out.
"The crash had indications of being a DDoS (distributed denial of service) 'attack'. We understand that this is very common and easy to do with botnets," U.K. lawmakers said in the report.
DDoS attacks are not particularly sophisticated and occur when a website is overloaded with traffic, causing it to crash. Botnets are a network of compromised computers, controlled without knowledge of the owner by malicious software.
"The U.S. and U.K. understanding of 'cyber' is predominantly technical and computer-network based. For example, Russia and China use a cognitive approach based on understanding of mass psychology and of how to exploit individuals," the report added.
The incident is not thought to have had a material impact on the outcome of the Brexit referendum though the committee stressed it would be "crucial" for Westminster to learn lessons from such technical issues when holding future votes.