According to Bloomberg, the Parliament along with the UK's National Cyber Security Centre are investigating an attack that started on Friday evening. To reduce the chances of being breached, remote access to email accounts has been disabled. In a statement, a parliament spokesperson said it was investigating "unauthorised attempts to access accounts of parliamentary networks users."
Parliament members took to Twitter to report on the removal of remote access and asked fellow members to text any urgent messages.
So far it looks like the attack has been largely unsuccessful at penetrating the government's servers. Still, the UK has had a rough couple of months. In May, UK hospitals were crippled by the WannaCry ransom attack.
As hackers become more sophisticated, are backed by nations and continue to get access to leaked government-held exploits, attacks like this will unfortunately become more common.